WO2012133976A1 - Method, server, terminal apparatus, and computer-readable recording medium for integrating plurality of nondeterministic finite automata for searching by simultaneously using plurality of regular expressions - Google Patents

Abstract

According to one embodiment of the present invention, provided are a server, a terminal apparatus, a computer-readable recording medium, and a method for integrating a first and a second nondeterministic finite automata, comprising the following steps: (a) acquiring first and second nondeterministic finite automatas; (b) determining whether a first transition set for moving a start state to an i state, within the first nondeterministic finite automata, and a second transition set for moving the start state to a j state within the second nondeterministic finite automata are identical; and (c) integrating the first and second nondeterministic finite automata by generating a state k in which the states i and j are combined in one, when the first transition set and the second transition set are identical.

Description

A method of merging a plurality of nondeterministic finite automata to retrieve using a plurality of regular expressions simultaneously, server, terminal device and computer readable recording medium

The present invention relates to a method for merging a plurality of nondeterministic finite automata (NFA) to retrieve a string using a plurality of regular expressions simultaneously, a server, a terminal device and a computer readable recording medium. will be. More specifically, the present invention converts a plurality of regular expressions into non-deterministic finite automata, respectively, and merges a plurality of non-deterministic finite automata using a state-covalent merge or transition-covalent merge scheme. A method, a server, a terminal device, and a computer readable recording medium for reducing and further improving the speed of retrieval.

Regular expression is a formal language used to express a set of strings with specific rules. Also known as regular expressions, regular expressions are used to express strings that you want to find when comparing or searching strings in computing devices such as computers. Used. According to formal language theory, which is a field of computer science dealing with regular expressions, regular expressions are based on ε, meaning a string with no content, and a single-character regular expression (for example, a, b, c, etc.) You can represent strings of various patterns by combining basic regular expressions using operators such as pasting (abc, bbbb, baba, etc.), selection (ab | c, ab | ba, etc.), and repetition (c *, etc.). have. In addition, since regular expressions may be too long or complicated, regular expressions with various extended syntaxes have been introduced for ease of use. The PCRE is implemented according to the method used in Perl, a computer programming language. These include Perl Compatible Regular Expressions and POSIX regular expressions defined in the standard for Unix-like computer operating systems.

On the other hand, when there are a plurality of regular expressions to be searched, the search time and memory usage vary greatly depending on how the search is performed. Therefore, a method for efficiently searching a string using a plurality of regular expressions is provided. Is being actively done.

First, as an example of the prior art of performing a string search using a plurality of regular expressions, a sequential search method has been introduced. This is a simple method of sequentially selecting and searching a plurality of given regular expressions one by one. Is converted to a finite automata and search is performed sequentially. This conventional technique has the advantage of being easy to perform because no separate preprocessing is required, but the time required to search a string in proportion to the number of regular expressions increases because there is one finite automata for each regular expression. There is a problem.

Next, a method of integrating into Nondeterministic Finite Automata (NFA) was introduced, which combines a single unified regular expression by concatenating all of the given multiple regular expressions using the selection (OR) operator "|". Create and convert unified regular expressions into non-deterministic finite automata (NFA). This conventional technique has the advantage of making a plurality of regular expressions into one unified regular expression by using only a relatively small amount of memory, but is subject to investigation in checking a particular sequence of characters in a string to be searched. There is a problem that the search time is increased because the state (that is, the active state) to be increased.

Next, a method of converting to Deterministic Finite Automata (DFA) was introduced, which converts a non-deterministic finite automata converted from the unified regular expression described above into a deterministic finite automata to keep the number of active states always one. This is how you do it. This prior art has the advantage of keeping the number of active states to one to speed up string searches and simplifying input string processing, but as the number of regular expressions increases, memory usage increases dramatically, There is a limitation in handling regular expressions, and since the conversion to deterministic finite automata is possible only after the nondeterministic finite automata corresponding to the integrated regular expression is made, the conversion to deterministic finite automata is completed. To add an expression, there is a problem of repeating the process of creating a non-deterministic finite automata and converting it to a deterministic finite automata.

Therefore, there is a need for a technique for enabling fast string search using a small amount of memory by using a non-deterministic finite automata and minimizing the number of active states.

The object of the present invention is to solve all the above-mentioned problems.

Another object of the present invention is to reduce the number of active states of the merged non-deterministic finite automata by comparing the states of the non-deterministic finite automata that are the subject of merging and combining the states common to each other in one state.

The present invention also aims to reduce the number of active states of the merged non-deterministic finite automata by comparing the transitions of the non-deterministic finite automata subjects to be merged and adding the common transition into one transition. do.

Representative configuration of the present invention for achieving the above object is as follows.

According to one aspect of the present invention, a method of merging a plurality of Nondeterministic Finite Automata (NFA) to search a string using a plurality of regular expressions simultaneously, comprising: (a) first and Obtaining first and second non-deterministic finite automata respectively corresponding to a second regular expression, (b) allowing the first and second non-deterministic finite automata share a start state and an end state, and wherein the first ratio Whether a first set of transitions consisting of a transition for moving said start state to state i in a deterministic finite automata and a second set of transitions consisting of a transition for moving said start state to state j in said second non-deterministic finite automata are equal to each other Determining whether the first transition set and the second transition set are the same; A step of generating a state k to merge the first and second non-deterministic finite automata - a method is provided that includes - the state k is replacing the state i and j.

According to another aspect of the present invention, a method of merging a plurality of Nondeterministic Finite Automata (NFA) to search a string using a plurality of regular expressions simultaneously, comprising: (a) first and Obtaining first and second non-deterministic finite automata respectively corresponding to a second regular expression, (b) allowing the first and second non-deterministic finite automata share a start state and an end state, and wherein the first ratio Is common between a first set of transitions that transition the start state to state i in a deterministic finite automata and a second set of transitions that transition the start state to state j in the second non-deterministic finite automata Determining whether at least one transition exists, and (c) the common between the first set of transitions and the second set of transitions. If it is determined that there is at least one transition, the state k reaching as a result of excluding the common transition from each of the first and second transition sets and moving from the start state by a common transition set consisting only of the common transitions is obtained. Generating and merging the first and second non-deterministic finite automata, wherein the state k is newly added within the merged non-deterministic finite automata.

According to another aspect of the invention, a server for merging a plurality of Nondeterministic Finite Automata (NFA) to search a string using a plurality of regular expressions simultaneously, the first and second An NFA obtainer for acquiring first and second non-deterministic finite automata corresponding to a regular expression, and allowing the first and second non-deterministic finite automata to share a start state and an end state, and wherein the first non-deterministic finite Whether a first set of transitions consisting of transitions for moving said starting state to state i in an automata and a second set of transitions consisting of transitions for moving said starting state to state j in said second non-deterministic finite automata are equal to each other; And if it is determined that the first set of transitions and the second set of transitions are the same, the image sums the states i and j into one. A NFA merging unit for generating state k and merging the first and second non-deterministic finite automata is provided, wherein state k replaces states i and j.

According to another aspect of the invention, a server for merging a plurality of Nondeterministic Finite Automata (NFA) to search a string using a plurality of regular expressions simultaneously, the first and second An NFA obtainer for acquiring first and second non-deterministic finite automata corresponding to a regular expression, and allowing the first and second non-deterministic finite automata to share a start state and an end state, and wherein the first non-deterministic finite A transition that is common between a first set of transitions that transitions the start state to state i in an automata and a second set of transitions that transitions the start state to state j in the second non-deterministic finite automata It is determined whether there is at least one, and the common transition between the first set of transitions and the second set of transitions If it is determined that there is at least one, the state k is reached by excluding the common transition from each of the first and second transition sets and moving from the start state by a common transition set consisting only of the common transitions. An NFA merging unit for merging the first and second non-deterministic finite automata is provided, wherein the state k is newly added in the merged non-deterministic finite automata.

According to another aspect of the present invention, a terminal apparatus for merging a plurality of non-deterministic finite automata (NFA) to search a string using a plurality of regular expressions simultaneously, comprising: An NFA obtainer for acquiring first and second non-deterministic finite automata corresponding to two regular expressions, and allowing the first and second non-deterministic finite automata to share a start state and an end state, and wherein the first non-deterministic Whether a first set of transitions consisting of a transition for moving said start state to state i in a finite automata and a second set of transitions consisting of a transition for moving said start state to state j in said second non-deterministic finite automata are equal to each other If it is determined that the first set of transitions and the second set of transitions are the same, sum the states i and j into one. An NFA merging unit for generating a state k and merging the first and second non-deterministic finite automata is provided, wherein the state k replaces the states i and j.

According to another aspect of the present invention, a terminal apparatus for merging a plurality of non-deterministic finite automata (NFA) to search a string using a plurality of regular expressions simultaneously, comprising: An NFA obtainer for acquiring first and second non-deterministic finite automata corresponding to two regular expressions, and allowing the first and second non-deterministic finite automata to share a start state and an end state, and wherein the first non-deterministic Transition common between a first set of transitions that transition the start state to state i in a finite automata and a second set of transitions that shift the start state to state j in the second non-deterministic finite automata Is determined whether there is at least one, and the common between the first set of transitions and the second set of transitions If it is determined that there is at least one, generating the state k that is reached as a result of moving from the start state by excluding the common transition from each of the first and second transition sets and by the common transition set consisting only of the common transitions. NFA merging unit for merging the first and second non-deterministic finite automata, wherein the state k is newly added in the merged non-deterministic finite automata.

In addition, there is further provided a computer readable recording medium for recording another method, a server, a terminal apparatus and a computer program for executing the method for implementing the present invention.

According to the present invention, since the number of active states can be reduced in merging a plurality of non-deterministic finite automata, the memory usage and the search speed can be improved when searching a string using a plurality of regular expressions simultaneously. Can be achieved.

1 is a diagram illustrating an internal configuration of a string search server according to an embodiment of the present invention.

FIG. 2 is a diagram exemplarily illustrating NFAs corresponding to two regular expressions according to an embodiment of the present invention.

3 is a reference diagram exemplarily illustrating a configuration of simply merging a plurality of NFAs according to the related art.

4 is a diagram exemplarily illustrating a configuration for performing state-sharing merging according to an embodiment of the present invention.

5 is a diagram exemplarily illustrating a configuration for performing a transition-covalent merging according to another embodiment of the present invention.

[Description of the code]

100: string search server

110: NFA Acquisition

120: NFA merger

130: search performer

140: communication unit

150: control unit

300: Simple Merged NFA

400: State-Shared Merged NFA

500: Transition-Shared Merged NFA

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention.

Configure String Search Server

Hereinafter, the internal structure of the string search server performing important functions for the implementation of the present invention and the function of each component will be described.

According to an embodiment of the present invention, a microprocessor is provided with memory means such as a personal computer (for example, a desktop computer, a notebook computer, etc.), a server, a workstation, a PDA, a web pad, a mobile phone, a smartphone, and the like. Therefore, any device having a computing capability can be adopted as the string search server 100 of the present invention.

1 is a diagram illustrating an internal configuration of a string search server according to an embodiment of the present invention.

Referring to FIG. 1, a string search server 100 according to an embodiment of the present invention may include an NFA acquisition unit 110 and a non-deterministic finite automata (NFA) merger. 120, a search execution unit 130, a communication unit 140, and a controller 150 may be included. According to an embodiment of the present invention, the NFA obtaining unit 110, the NFA merging unit 120, the search performing unit 130, the communication unit 140 and the control unit 150 at least some of them are external systems (not shown) Program modules). Such program modules may be included in the string search server 100 in the form of an operating system, an application module, and other program modules, and may be physically stored on various known storage devices. In addition, such program modules may be stored in a remote storage device that can communicate with the string search server 100. On the other hand, such program modules include, but are not limited to, routines, subroutines, programs, objects, components, data structures, etc. that perform particular tasks or execute particular abstract data types, described below, in accordance with the present invention.

First, according to an embodiment of the present invention, the NFA obtaining unit 110 performs a function of obtaining an NFA corresponding to a regular expression to be searched. Here, it may be assumed that the regular expression to be searched is obtained by the NFA acquiring unit 100 only after being converted into NFA (in this case, the conversion process may be performed by a predetermined regular expression converting unit (not shown). It is also possible to assume that the regular expression itself, which is a search target, is obtained by the NFA obtaining unit 100 and then converted into NFA by the NFA obtaining unit 100. In general, the NFA consists of a state set S, a transition set Σ, a transition function δ, a start state s ₀ , and an end state set F. Here, both the start state and the end state belong to state set S. In addition, as in the present invention, if the character string is searched using a regular expression, the transition character Σ may be {0, 1, 2, ..., 255} since the input character may correspond to any ASCII code value. Can be.

In order to convert regular expressions to NFA, some regular expression conversion techniques are required, such as "Regular expressions into finite automata" by A. Bruggemann-Klein and published in 1993 in Theoretical Computer Science. May be referred to (the content of the paper should be considered to be incorporated in its entirety). This paper describes a method for converting regular expressions into Glushkov automata, which is a relatively simple form of automata. Of course, the regular expression conversion technique applicable to the present invention is not limited to the method described in the above paper, and various modifications may be applied to implement the present invention. For example, the regular expression converting unit 110 according to an embodiment of the present invention may convert the regular expression into other forms such as Thompson automata, Follow automata, and Antimirov automata. have. However, hereinafter, the present invention will be described on the basis of the Gluikov automata in order to maintain the consistency of the detailed description of the invention.

FIG. 2 is a diagram exemplarily illustrating NFAs corresponding to two regular expressions according to an embodiment of the present invention.

According to an embodiment of the present invention, it is assumed that the first and second regular expressions to be converted are "([ab] {3} | dd) a" and "[bc] aa | ddd", respectively. Here, the first regular expression "([ab] {3} | dd) a" is either three consecutive characters (that is, represented by {3}) is either one of a and b ([ab]) or continuous Both characters are d, followed by a string, and the second regular expression, "[bc] aa | ddd", is the continuation of the first character of either b or c, followed by Refers to a string in which one or two characters are a or all three consecutive characters are d.

According to an embodiment of the present invention, the first and second regular expressions may be converted to the first and second NFAs ((a) and (b) of FIG. 2, respectively). Referring to FIG. The circle containing the indicates the state of the NFA, the arrow and the letter together with it indicates the transition (이동) to move from one state to another along the arrow when the character is entered, two of the circles containing numbers The concentric circles represent the end state, which means that the character string to be searched is found when the end state is reached.

Next, according to an embodiment of the present invention, the NFA merging unit 120 uses a plurality of NFAs generated as a result of converting a plurality of regular expressions to search for a string using a plurality of regular expressions simultaneously. Merge into the integrated NFA. For example, the NFA merger 120 according to an embodiment of the present invention may perform a function of reducing the number of active states of the merged NFA by combining the common state or transition between two NFAs to be merged into one. Can be. Hereinafter, a method of merging NFAs according to the present invention will be described in more detail.

3 is a reference diagram exemplarily illustrating a configuration of simply merging a plurality of NFAs according to the related art.

Referring to FIG. 3, it may be assumed that the first and second NFAs illustrated in FIG. 2 are merged. In this case, a start state and an end state of each of the first and second NFAs may be set. It can be seen that by merging with states, the first and second NFAs are simply merged. This simple merged NFA, in the prior art described above, is the case where the first and second regular expressions corresponding to the first and second NFAs are respectively concatenated with the OR operator "|" and then converted to NFA. It becomes NFA of the same structure. In fact, only state 0, 1, 2, 3, 4, and 5 of the simple merged NFA 300 of FIG. 3 are the same as the first NFA of FIG. 2A, and the simple merged NFA of FIG. If only state 0, 6, 7, 4, 8 and 9 of 300 is separated, it can be seen that it is the same as the second NFA of FIG.

In other words, simple merging of multiple NFAs results in a particular sequence of characters in the string to be searched, as in the prior art, where multiple regular expressions are concatenated with the OR operator "|" and then converted to NFA. In examining the problem, there is a problem of increasing the number of states to be investigated, that is, active states. For example, if the letter d is input in state 0 310 of the simple merged NFA 300 of FIG. 3, state 5 310 may move from state 0 310 to state 5 330 and 8 350. ) And 8 (350) may be active, and if the letter b is entered in state 0 (310), then state 1 (320) and state (320) may move from state 0 (310) to state 1 (320). And 6 330 may be active.

As such, when the number of active states is increased, the search speed is slowed down because the next input character needs to be examined and the next state is determined. It becomes slower. Therefore, there is a need for a method that can reduce the number of active states in the process of merging NFA.

First, according to an embodiment of the present invention, the NFA merging unit 120 compares the states of a plurality of NFAs to be merged, sums the states common to the plurality of NFAs into one state, and the plurality of NFAs are mutually different. State-sharing merging can be performed to enable sharing of common state. Specifically, according to an embodiment of the present invention, the NFA merging unit 120 compares the following states connected to the start states of the plurality of NFAs to be merged, and adds all the states that can be summed, and then connected again. State-sharing merge can be performed by comparing states.

In more detail, the NFA merger 120 according to an embodiment of the present invention merges the first and second NFAs such that the first and second NFAs that are the targets of the merge share the start state and the end state. In this merged NFA, it is possible to determine whether the first set of transitions consisting of transitions for moving the start state to state i and the second set of transitions consisting of transitions for moving the start state to state j are the same. As a result, if it is determined that the first set of transitions and the second set of transitions are the same, that is, it is determined that the states i and j are the same state, so-called state k that combines the states i and j into one to generate states i and j Replace with state k and allow the first and second NFAs to share state k. Here, according to an embodiment of the present invention, the state k generated as described above may be generated so as to be connected to both a state reachable from a state i and a state reachable from a state j.

In addition, the NFA merger 120 according to an embodiment of the present invention moves the third set of transitions and the state k to the state m, which consists of a transition for moving the state k to the state l in the merged non-deterministic finite automata. It is determined whether or not the fourth set of transitions consisting of transitions is equal to each other, and if it is determined that the third set of transitions and the fourth set of transitions are the same, a state n is obtained by adding states l and m to state n and m to state n. And let the first and second NFAs share state n.

Also, in the first and second non-deterministic finite automata, a route in which the start state reaches state i or j by the first or second set of transitions is referred to as an additional route other than the default route. If the state i or j can be reached, the NFA merger 120 according to an embodiment of the present invention is a first additional route consisting of all additional routes that can reach state i within the first non-deterministic finite automata. The first and second non-deterministic finite automata can be merged such that the state k is generated if the second set of additional roots consisting of the set and all additional routes that can reach state j within the second non-deterministic finite automata is the same. .

Here, the root means a predetermined path specified by all the states and transitions that pass through until reaching state i or j. In this specification, a route for which the starting state reaches state i or j by the first or second set of transitions is referred to as a primary route, and a route that reaches state i or j as a route other than the primary route is called an additional route. This name is for convenience of explanation, and it should be noted that a root, which is the default route, may be referred to as an additional route according to an access criterion, and vice versa.

Similarly, in a first and second non-deterministic finite automata, a route in which state k reaches state l or m by the third or fourth set of transitions is referred to as an additional route other than the default route. If the state l or m can be reached, then the NFA merger 120 according to an embodiment of the present invention is a third additional route consisting of all additional routes that can reach state l within the first non-deterministic finite automata. State n can be generated if the set and the fourth additional route set, which consists of all additional routes that can reach state m within the second non-deterministic finite automata, are identical.

4 is a diagram exemplarily illustrating a configuration for performing state-sharing merging according to an embodiment of the present invention. For reference, in the embodiment of FIG. 4, state-covalent merging of the first and second NFAs shown in FIGS. 2A and 2B, respectively.

First, referring to the first and second NFAs shown in FIGS. 2A and 2B, respectively, a first set of transitions consisting of transitions for moving the start state 210 of the first NFA to state 5230 is described. Since the second set of transitions {d} consisting of the transitions moving {d} and the starting state 215 of the second NFA to state 4 (250) are the same, that is, state 5 230 of the first NFA and Since state 4 (250) of the second NFA is a state that is reached as a result of moving by the input letter d in the state 0 (210, 215), which is a starting state, state 5 (230) of the first NFA and the second NFA State 4 (250) may be referred to as the same state. For reference, when the first and second NFAs of FIG. 3 are simply merged, the state 5 (330) and 8 (350) are the same state. It can be said.

Referring to FIG. 4, the NFA merging unit 120 according to an embodiment of the present invention shows a state in which state-sharing merging that combines the states common between the first and second NFAs into one state is performed as described above. . That is, in the state-shared merged NFA 400, by adding the states 5 330 and 8 350 of the simple merged NFA 300 of FIG. 3 into one, leaving only the state 5 460, state 0 ( In operation 410, it may be confirmed that even when the letter d is input, the active state may be maintained as one (that is, state 5 (460)).

4, the NFA merger 120 according to an embodiment of the present invention compares the state 3 (480) and the state 9 (490) of the next state after the state 5 (460), and the two states are mutually different. If they are the same state, they can be combined into one state. However, even though state 3 (480) and state 9 (490) are both states that the letter d can be reached twice in succession from state 0, state 3 (480) can be entered even if other strings such as aaa and bab are entered. Since the state can be reached, the state 3 480 and the state 9 490 are not the same state. Thus, state 3 (480) and state 9 (490) cannot be summed into one state.

Next, according to another exemplary embodiment of the present invention, the NFA merging unit 120 compares the transitions of a plurality of NFAs to be merged, and adds a common transition between the plurality of NFAs into a single transition to form a plurality of NFAs. Transition-sharing merging may be performed to share a common transition with each other. Specifically, according to another embodiment of the present invention, the NFA merging unit 120 compares all the transitions that can be added by comparing the transitions of moving the start states of the plurality of NFAs to be merged to the next state, and then adds them again. Transition-covalent merging can then be performed by comparing the transitions to move to the connected state.

In more detail, the NFA merger 120 according to another embodiment of the present invention merges the first and second NFAs so that the first and second NFAs that are the targets of the merge share the start state and the end state. And at least one transition in common between the first set of transitions consisting of a transition for moving the start state to state i and the second set of transitions for moving the start state to state j within the merged NFA. If it is determined that there is at least one common transition between the first set of transitions and the second set of transitions, it is possible to exclude the common transitions in each of the first and second set of transitions, It is possible to generate a state k that can be moved and reached from the start state by a common set of transitions. Further, according to another embodiment of the present invention, the state k generated as described above is generated to be connected by each corresponding transition with a state that can be reached by moving from state i and a state that can be reached by moving from state j. Can be.

In addition, the NFA merger 120 according to another embodiment of the present invention may include a third set of transitions for moving the state k to the state l and a fourth set of transitions for the state k to the state m in the merged non-deterministic finite automata. If it is determined whether there is at least one common transition between them, and if it is determined that at least one common transition exists between the third set of transitions and the fourth set of transitions, a transition common to each of the third and fourth set of transitions is determined. It is possible to generate a state n that arrives as a result of transitioning from state k by a common set of transitions that exclude only a common transition.

On the other hand, in the first and second non-deterministic finite automata, a route in which the start state reaches state i or j by the first or second transition set is referred to as a default route through an additional route other than the default route. If the state i or j can be reached, the NFA merger 120 according to an embodiment of the present invention is a first additional route consisting of all additional routes that can reach state i within the first non-deterministic finite automata. If the second additional route set, which consists of the set and all additional routes that can reach state j within the second non-deterministic finite automata, is equal, exclude state common and create a state k in each of the first and second transition sets. To merge the first and second non-deterministic finite automata.

Similarly, in a first and second non-deterministic finite automata, a route in which state k reaches state l or m by the third or fourth set of transitions is referred to as an additional route other than the default route. If the state l or m can be reached, then the NFA merger 120 according to an embodiment of the present invention is a third additional route consisting of all additional routes that can reach state l within the first non-deterministic finite automata. If the fourth additional route set, which consists of the set and all additional routes that can reach state m within the second non-deterministic finite automata, is equal, then exclude the common transition in each of the third and fourth transition sets and generate state n. Can be.

5 is a diagram exemplarily illustrating a configuration for performing a transition-covalent merging according to another embodiment of the present invention. For reference, the embodiment of FIG. 5 assumes a case of transition-covalent merging of the first and second NFAs illustrated in FIGS. 2A and 2B, respectively.

2 and 5, a first set of transitions {a, b} and a start state 215 of a second NFA, which are transitions that move the start state 210 of the first NFA to state 1 220, are described. According to an embodiment of the present invention, since the second transition set {b, c} consisting of transitions to state 1 240 includes a transition by the input letter b, the first and second transitions Each of the sets may exclude transition by input letter b and add state 8 570 that can be reached by transition by input letter b. More specifically described as follows.

When the letter a is input in the state 0 (210) that is the start state of the first NFA of FIG. 2 (a), the state moves to state 1 (220), but state 0 (the state that is the start state of the second NFA of FIG. In 215, even if the letter a is input, there is no corresponding transition, and thus stays in state 0 (215). In addition, even if the letter c is input in the state 0 (210), which is the start state of the first NFA of FIG. 2 (a), there is no corresponding transition, so the state remains as it is in the state 0 (210). 2 In the state 0 (215), which is the start state of the NFA, when the letter c is input, the state moves to the state 1 240. For this reason, since the state 1 (220) of the first NFA and the state 1 (240) of the second NFA are not identical to each other, even in the state-shared merged NFA of FIG. It must exist.

However, when the letter b is input in the state 0 (210, 215) in which both the first and second NFAs are started, the state moves to the state 1 (220, 240), which is limited to the case where the input character is b only. State 1 (220) of the 1 NFA and state 1 (240) of the second NFA can be viewed as the same state, that is, that is, from the start state 210 of the first NFA to state 1 (220) This means that the transition by the input letter b and the transition by the input letter b from the start state 215 of the second NFA to the state 1 240 are the same.

Referring to FIG. 5, the NFA merger 120 according to another embodiment of the present invention may perform a transition-covalent merge that combines a common transition between the first and second NFAs into one transition as described above. That is, in the transition-covalent merged NFA 500, the transition by the input letter b during the transition from the state 0 410, which is the start state of the state-shared merged NFA 400 of FIG. 4, to the state 1 420, is performed. Deletes and transitions from state 0 (410) to state 6 (440) are deleted by input letter b, while state 0 (410) is a new state that is reached as a result of transition by input letter b. By adding 570, unlike the simple merged NFA 300 of FIG. 3 or the state-covalent merged NFA 400 of FIG. 4, in state 0 510, the character is any of a, b, and c. Even if it is input, it can be confirmed that the active state can be suppressed to one.

Meanwhile, according to an embodiment of the present invention, the search performing unit 130 performs a function of searching for a string using the NFA merged by the NFA merging unit 120.

For example, it may be assumed that a desired string is searched for in a string of "gjekf3jmbabad1f" using an NFA in which both the state-shared merge and the transition-shared merge shown in FIG. 5 are performed. In this case, the character string "gjekf3jmbabad1f" may be read one by one starting from the state 0 (510) which is a start state. According to this, since the first character is g but there is no transition by the input character g in the state 0 (510), the first character stays in the state 0 and the second character is examined. The second character is j, but in state 0 (510) there is no transition by input character j, so it stays in state 0 and examines the third character. After checking state 0 to gjekf3jm in this way, the next character is b, which moves to state 8 (570) following the transition by the input character b that exists in state 0 (510), followed by a sequence of inputs. By the letters a, b, and a, state 4 (ie, the end state) is reached, which means that the desired string "baba" is found. According to this, much faster searching is achieved by achieving much less active state than conventional searching methods.

Next, according to an embodiment of the present invention, the communication unit 140 may perform a function to enable the string search server 100 of the present invention to communicate with an external device.

Finally, the controller 150 according to an embodiment of the present invention performs a function of controlling the flow of data between the NFA obtaining unit 110, the NFA merging unit 120, and the search performing unit 130. That is, the controller 150 controls the flow of data from the outside or between the respective components of the string search server 100, so that the NFA obtaining unit 110, the NFA merging unit 120, the search performing unit 130, And the communication unit 140 to perform a unique function.

In the above, the process of acquiring, merging, and searching for a string of NFAs has been described based on the embodiment performed by the server. However, the configuration of the present invention is not necessarily limited to the above embodiment. Not shown). For example, a process of acquiring and / or merging NFAs and searching for a string may be performed by a predetermined application installed in the terminal device.

Embodiments according to the present invention described above may be implemented in the form of program instructions that may be executed by various computer components, and may be recorded in a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the computer-readable recording medium may be those specially designed and configured for the present invention, or may be known and available to those skilled in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs, DVDs, and magneto-optical media such as floptical disks. media), and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the process according to the invention, and vice versa.

Although the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided to assist in a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations can be made from these descriptions.

Accordingly, the spirit of the present invention should not be limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the appended claims, fall within the scope of the spirit of the present invention. I will say.

Claims (39)

1. A method of merging a plurality of nondeterministic finite automata (NFAs) to search a string using a plurality of regular expressions simultaneously.

   (a) obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively,

   (b) a first set of transitions comprising a transition for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata Determining whether a second set of transitions consisting of transitions for moving the start state to state j in a second non-deterministic finite automata is equal to each other, and

   (c) if it is determined that the first set of transitions and the second set of transitions are the same, generating a state k that combines the states i and j into one and merging the first and second non-deterministic finite automata-the state k Replaces states i and j above −

   How to include.
2. The method of claim 1,

   In the step (c),

   In the first and second non-deterministic finite automata, a route in which the starting state reaches the state i or j by the first or second set of transitions is added as the default route when the route is other than the default route. If the state i or j can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state i or j, within the first non-deterministic finite automata When the first additional route set consisting of all additional routes that can reach state i and the second additional route set consisting of all additional routes that can reach state j within the second non-deterministic finite automata are equal Merge the first and second non-deterministic finite automata by causing the state k to be generated.
3. The method of claim 1,

   Before step (a) above,

   Converting the first and second regular expressions into the first and second non-deterministic finite automata, respectively

   How to include more.
4. The method of claim 1,

   And wherein the non-deterministic finite automata is any one of a Glushkov automata, a Thompson automata, a Follow automata, and an Antimirov automata.
5. The method of claim 1,

   In the step (c),

   And the state k is generated to be connected to both a state that can be reached by moving from the state i and a state that can be reached by moving from the state j.
6. The method of claim 1,

   (d) whether or not a third set of transitions consisting of transitions for moving said state k to state l and a fourth set of transitions moving said state k to state m are identical in said merged non-deterministic finite automata; Judging, and

   (e) if it is determined that the third set of transitions and the fourth set of transitions are the same, generating a state n that sums the states l and m into one, wherein the state n replaces the states l and m;

   Method further comprising a.
7. The method of claim 6,

   In the step (e),

   In the first and second non-deterministic finite automata, a route in which the state k reaches the state l or m by the third or fourth set of transitions is added as the default route when the route is other than the default route. If the state l or m can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state l or m, within the first non-deterministic finite automata When the third additional route set consisting of all additional routes that can reach state l and the fourth additional route set consisting of all additional routes that can reach state m within the second non-deterministic finite automata are equal And the state n is generated.
8. The method of claim 1,

   (f) merging a third non-deterministic finite automata into the merged non-deterministic finite automata

   Method further comprising a.
9. The method of claim 1,

   (g) sequentially inputting a string to be searched into the merged non-deterministic finite automata so that the state of the merged non-deterministic finite automata can transition, and the merged non-deterministic finite automata reaches an end state If it is determined that the desired string is included in the string to be searched

   Method further comprising a.
10. A method of merging a plurality of nondeterministic finite automata (NFAs) to search a string using a plurality of regular expressions simultaneously.

    (a) obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively,

    (b) a first set of transitions comprising a transition for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata Determining whether there is at least one transition common between a second set of transitions consisting of transitions to move the start state to state j in a second non-deterministic finite automata, and

    (c) if it is determined that at least one common transition exists between the first set of transitions and the second set of transitions, only the common transition is excluded from each of the first and second set of transitions. Merging the first and second non-deterministic finite automata by generating a state k that arrives as a result of moving from the starting state by a common set of transitions, wherein state k is newly added within the merged non-deterministic finite automata

    How to include.
11. The method of claim 10,

    In the step (c),

    In the first and second non-deterministic finite automata, a route in which the starting state reaches the state i or j by the first or second set of transitions is added as the default route when the route is other than the default route. If the state i or j can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state i or j, within the first non-deterministic finite automata When the first additional route set consisting of all additional routes that can reach state i and the second additional route set consisting of all additional routes that can reach state j within the second non-deterministic finite automata are equal The first and second amorphous states are excluded from each of the first and second set of transitions so that the state k is generated. Method of merging enemy finite automata.
12. The method of claim 10,

    Before step (a) above,

    Converting the first and second regular expressions into the first and second non-deterministic finite automata, respectively

    How to include more.
13. The method of claim 10,

    And wherein the non-deterministic finite automata is any one of a Glushkov automata, a Thompson automata, a Follow automata, and an Antimirov automata.
14. The method of claim 10,

    In the step (c),

    And the state k is generated to be connected to both a state that can be reached by moving from the state i and a state that can be reached by moving from the state j.
15. The method of claim 10,

    (d) a transition common in the merged non-deterministic finite automata between a third set of transitions comprising the transition of state k to state l and a fourth set of transitions comprising the transition of state k to state m Determining whether at least one exists,

    (e) if it is determined that at least one common transition exists between the third set of transitions and the fourth set of transitions, the common transition is excluded from each of the third and fourth set of transitions and only the common transition is obtained. Merging the first and second non-deterministic finite automata by generating state n reaching a result of the transition from state k by a common set of transitions, wherein state n is newly added within the merged non-deterministic finite automata

    How to include.
16. The method of claim 15,

    In the step (e),

    In the first and second non-deterministic finite automata, a route in which the state k reaches the state l or m by the third or fourth set of transitions is added as the default route when the route is other than the default route. If the state l or m can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state l or m, within the first non-deterministic finite automata When the third additional route set consisting of all additional routes that can reach state l and the fourth additional route set consisting of all additional routes that can reach state m within the second non-deterministic finite automata are equal Generating the state n without excluding the common transition from each of the third and fourth transition sets.
17. The method of claim 10,

    (f) merging a third non-deterministic finite automata into the merged non-deterministic finite automata

    Method further comprising a.
18. The method of claim 10,

    (g) sequentially inputting a string to be searched into the merged non-deterministic finite automata so that the state of the merged non-deterministic finite automata can transition, and the merged non-deterministic finite automata reaches an end state If it is determined that the desired string is included in the string to be searched

    Method further comprising a.
19. A server that merges multiple nondeterministic finite automata (NFAs) to retrieve strings using multiple regular expressions simultaneously.

    An NFA obtainer for obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively, and

    A first set of transitions and a second ratio consisting of transitions for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata In a deterministic finite automata, it is determined whether a second set of transitions consisting of transitions for moving the start state to state j is the same, and if it is determined that the first set of transitions and the second set of transitions are the same, the state i and NFA merger for generating state k sum of j into one to merge the first and second non-deterministic finite automata, wherein state k replaces states i and j

    Server comprising.
20. The method of claim 19,

    The NFA merger,

    In the first and second non-deterministic finite automata, a route in which the starting state reaches the state i or j by the first or second set of transitions is added as the default route when the route is other than the default route. If the state i or j can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state i or j, within the first non-deterministic finite automata When the first additional route set consisting of all additional routes that can reach state i and the second additional route set consisting of all additional routes that can reach state j within the second non-deterministic finite automata are equal Merge the first and second non-deterministic finite automata by causing the state k to be generated.
21. The method of claim 19,

    A regular expression converter for converting the first and second regular expressions into the first and second non-deterministic finite automata, respectively

    Server further comprising a.
22. The method of claim 19,

    Wherein the non-deterministic finite automata is any one of a Glushkov automata, a Thompson automata, a Follow automata, and an Antimirov automata.
23. The method of claim 19,

    And the state k is generated so as to be connected with both a state reachable from the state i and a state reachable from the state j.
24. The method of claim 19,

    The NFA merger,

    Determining whether a third set of transitions consisting of a transition for moving the state k to state l and a fourth set of transitions for moving the state k to state m are the same in the merged non-deterministic finite automata, And if it is determined that the third set of transitions and the fourth set of transitions are the same, generating a state n that sums the states l and m into one, wherein the state n replaces the states l and m.
25. The method of claim 24,

    The NFA merger,

    In the first and second non-deterministic finite automata, a route in which the state k reaches the state l or m by the third or fourth set of transitions is added as the default route when the route is other than the default route. If the state l or m can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state l or m, within the first non-deterministic finite automata When the third additional route set consisting of all additional routes that can reach state l and the fourth additional route set consisting of all additional routes that can reach state m within the second non-deterministic finite automata are equal And the state n is generated.
26. The method of claim 19,

    The NFA merger,

    And merge a third non-deterministic finite automata into the merged non-deterministic finite automata.
27. The method of claim 19,

    The character string to be searched is sequentially input to the merged non-deterministic finite automata so that the state of the merged non-deterministic finite automata can transition. Search execution unit that determines that the desired string is included in the target string of the

    Server further comprising a.
28. A server that merges multiple nondeterministic finite automata (NFAs) to retrieve strings using multiple regular expressions simultaneously.

    An NFA obtainer for obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively, and

    A first set of transitions and a second ratio consisting of transitions for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata It is determined whether there is at least one common transition between a second set of transitions of transitions that move the start state to state j in a deterministic finite automata, and the common between the first set of transitions and the second set of transitions. If it is determined that at least one transition is present, the state k is reached as a result of moving from the start state by excluding the common transition from each of the first and second transition sets, and by the common transition set consisting only of the common transitions. NFA merger for generating the first and the second non-deterministic finite automata to merge- The state k is newly added in the merged non-deterministic finite automata.

    Server comprising.
29. The method of claim 28,

    The NFA merger,

    In the first and second non-deterministic finite automata, a route in which the starting state reaches the state i or j by the first or second set of transitions is added as the default route when the route is other than the default route. If the state i or j can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state i or j, within the first non-deterministic finite automata When the first additional route set consisting of all additional routes that can reach state i and the second additional route set consisting of all additional routes that can reach state j within the second non-deterministic finite automata are equal The first and second amorphous states are excluded from each of the first and second set of transitions so that the state k is generated. A server characterized by merging enemy finite automata.
30. The method of claim 28,

    A regular expression converter for converting the first and second regular expressions into the first and second non-deterministic finite automata, respectively

    Server further comprising a.
31. The method of claim 28,

    Wherein the non-deterministic finite automata is any one of a Glushkov automata, a Thompson automata, a Follow automata, and an Antimirov automata.
32. The method of claim 28,

    And the state k is generated so as to be connected with both a state reachable from the state i and a state reachable from the state j.
33. The method of claim 28,

    The NFA merger,

    There is at least one transition common in the merged non-deterministic finite automata between a third set of transitions consisting of a transition to move state k to state l and a fourth set of transitions to move state k to state m And if it is determined that at least one common transition exists between the third set of transitions and the fourth set of transitions, the common transition is excluded from each of the third and fourth set of transitions, and the common transition is excluded. Generating a state n arriving as a result of the transition from the state k by a common set of transitions consisting only of the transitions, wherein the state n is newly added in the merged non-deterministic finite automata.
34. The method of claim 33, wherein

    The NFA merger,

    In the first and second non-deterministic finite automata, a route in which the state k reaches the state l or m by the third or fourth set of transitions is added as the default route when the route is other than the default route. If the state l or m can be reached via a route, the primary route and the additional route are specified by all states and transitions that pass through the state l or m, within the first non-deterministic finite automata When the third additional route set consisting of all additional routes that can reach state l and the fourth additional route set consisting of all additional routes that can reach state m within the second non-deterministic finite automata are equal Generate the state n without excluding the common transition from each of the third and fourth transition sets.
35. The method of claim 28,

    The NFA merger,

    And merge a third non-deterministic finite automata into the merged non-deterministic finite automata.
36. The method of claim 28,

    The character string to be searched is sequentially input to the merged non-deterministic finite automata so that the state of the merged non-deterministic finite automata can be transitioned. Search execution unit that determines that the desired string is included in the target string of the

    Server further comprising a.
37. A terminal device for merging a plurality of non-deterministic finite automata (NFAs) to search a string using a plurality of regular expressions simultaneously.

    An NFA obtainer for obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively, and

    A first set of transitions and a second ratio consisting of transitions for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata In a deterministic finite automata, it is determined whether a second set of transitions consisting of transitions for moving the start state to state j is the same, and if it is determined that the first set of transitions and the second set of transitions are the same, the state i and NFA merger for generating state k sum of j into one to merge the first and second non-deterministic finite automata, wherein state k replaces states i and j

    Terminal device comprising a.
38. A terminal device for merging a plurality of non-deterministic finite automata (NFAs) to search a string using a plurality of regular expressions simultaneously.

    An NFA obtainer for obtaining first and second non-deterministic finite automata corresponding to the first and second regular expressions, respectively, and

    A first set of transitions and a second ratio consisting of transitions for causing the first and second non-deterministic finite automata to share a start state and an end state, and shifting the start state to state i within the first non-deterministic finite automata It is determined whether there is at least one common transition between a second set of transitions of transitions that move the start state to state j in a deterministic finite automata, and the common between the first set of transitions and the second set of transitions. If it is determined that at least one transition is present, the state k is reached as a result of moving from the start state by excluding the common transition from each of the first and second transition sets, and by the common transition set consisting only of the common transitions. NFA merger for generating the first and the second non-deterministic finite automata to merge- The state k is newly added in the merged non-deterministic finite automata.

    Terminal device comprising a.
39. A computer-readable recording medium having recorded thereon a computer program for executing the method according to any one of claims 1 to 18.

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