CN103150200A - Computer language transformation system and transformation method from C language to MSVL (Modeling, Simulation and Verification Language) - Google Patents

Abstract

The invention relates to a computer language transformation system. The computer language transformation system is used for transforming C language program into MSVL (Modeling, Simulation and Verification Language) program, and comprises a lexical analysis module, a syntax analysis module and a transformation processing module, wherein the lexical analysis module is used for transforming character sequences into word sequences; the character sequences comprise definitions of key words, identification characters, constants, operators, header files and comment lines in C language; the syntax analysis module is used for identifying specific sentences in C language based on related lexical rules of C language specified in yacc (Yet Another Compiler Compiler); and the transformation processing module is used for transforming C language into MSVL language according to a language transformation rule between C language and MSVL language.

Description

A computer language conversion system and conversion method from C language to MSVL language

technical field

The invention relates to the technical field of computer programming language C language, in particular to a conversion method from a C language structured statement to an MSVL corresponding statement.

Background technique

C language is a general-purpose, procedural programming language widely used in the development of systems and application software. It has the characteristics of high efficiency, flexibility, rich functions, strong expressive power and high portability, and is very popular among programmers. The new international standard draft C11 of C language officially announced by ISO in 2011 improves the compatibility with C++ and adds new features to C language. New features include support for multi-threading, support for Unicode based on the ISO/IEC TR19769:2004 specification, and provide more macro definitions and static declaration functions for querying the characteristics of floating-point numbers. Although the C language is widely used in the development of various systems and software, it is a huge challenge to ensure its correctness and security. Model checking is an effective means to verify the correctness of the system, but it has become a difficulty and challenge to extract the abstract model of the C language program.

As a system modeling and verification tool, sequential logic has been widely used in software engineering, digital circuit design and other fields. Projected Temporal Logic (PTL) extends ITL. Temporal logic language MSVL is an executable subset of PTL. It is a sequential logic programming that integrates modeling (Modeling), simulation (Simulation) and verification (Verification). Language, which unifies the modeling and property description of the system in the same logical framework, and verifies the nature of the system through model checking technology. Projected sequential logic is also extremely useful in formal description and verification of real-time and hybrid systems, especially safety-critical systems. For example, the manned spaceflight system is a complex hybrid real-time system. In order to ensure the safety and reliability of the system, traditional The test method of the test is far from meeting the requirements, and it is very useful to adopt formal verification technology.

In addition, the language structure of the projected sequential logic programming language MSVL is very similar to the C language, and it is easy to generate the corresponding conversion relationship. By realizing the conversion from C language to MSVL language, and verifying the converted target program, using the idea of equivalent conversion, the extraction of the formal model of C language can be realized, and the model can be tested for the model, which will greatly improve the Improve the security and reliability of C language programs.

Contents of the invention

The invention provides a computer language conversion system, which can convert C language into MSVL language to detect programs in C language. It specifically includes, a computer language conversion system, which is used to convert a C language program into an MSVL language program, characterized in that: it includes,

A lexical analysis module, which converts the character sequence into a word sequence, and the character sequence includes definitions of keywords, identifiers, constants, operators, header files and comment lines in the C language;

The grammatical analysis module, which is based on the relevant lexical rules of the C language specified in yacc, and then identifies specific sentences in the C language;

The conversion processing module converts the C language into the MSVL language according to the language conversion rule between the C language and the MSVL language.

The present invention also provides a conversion method from C language to MSVL language, which provides a lexical analysis module, a syntax analysis module and a conversion processing module, and is characterized in that: the method includes the following steps;

The first step: the C language program is imported into the lexical analysis module, and this step includes converting the character sequence into a word sequence, and the character sequence includes keywords, identifiers, constants, operators, header files and comment lines in the C language definition;

Step 2: import the word stream obtained in step 1 into the syntax analysis module, which step includes identifying specific sentences in the C language based on the relevant lexical rules of the C language specified in the yacc;

The third step: convert the C language statement sequence identified by the second step grammatical analysis into a corresponding MSVL statement in the conversion processing module according to the corresponding conversion rules;

Step 4: Connect the obtained MSVL statement sequence with the sequence operator ";" to obtain the MSVL program.

On the basis of the above technical solution, the structured statements in the C language described in the syntax analysis module include basic expression statements, while statements, if statements, if-else statements, for statements, switch statements, printf statements and scanf statements .

On the basis of the above technical solution, the while statement of the structured statement in the C language described in the syntax analysis module, the loop body of the for statement, the if statement, and the conditional statement of the if-else statement are a statement block.

On the basis of the above technical solution, the language conversion rules between the C language and the MSVL language include expression conversion rules, sentence conversion rules and sentence block conversion rules. .

On the basis of the above-mentioned technical scheme, the transformation rule of described expression is as follows:

Convert the expression, assuming that x and y are standard symbols, and e represents a constant or variable, the reference rules are as follows:

If the expression is e, convert it to MSVL expression and return e;

If the expression is [x++|x--], it will be transformed into MSVL statement x:=x+1and skip or x:=x-1and skip;

If the expression is x=y, it will be transformed into MSVL statement x:=y and skip;

If the expression is x==y, it will be transformed into MSVL statement x==y;

If the expression is x[+,-,*,/,%,!=]y, it will be converted to MSVL expression x[+,-,*,/,%,!=]y;

If the expression is x*=y(*=[<|>]), it will be converted to MSVL expression x=y or x*y;

If the expression is x[+|-|*|/|%]=y, it is transformed into x:=x[+|-|*|/|%]y and skip;

If the expression is x&&y, it will be transformed into MSVL statement x and skip;

If the expression is x||y, it is transformed into the MSVL statement x or y;

If the expression is x, y, it will be converted into MSVL statement x, y;

If the expression is (x), it is converted into an MSVL statement as (x);

On the basis of the above technical solutions,

To convert the basic statement, assuming that exp is a constant expression, block is a statement block, s represents a complete statement, x is a variable, and parameter represents a string, the rules are as follows:

If the statement is an empty statement, it is converted to an empty statement;

If the statement is exp, it is converted to exp;

If the statement is x=exp, it is transformed into x:=exp and skip;

If the statement is an if statement, use the conversion rules of the IF statement to convert the statement;

If the statement is while(exp){block}, it will be converted into MSVL statement while(exp){block};

If the statement is an int declaration statement, use the conversion rules of the declaration statement to convert the statement;

If the statement is for(s exp1;exp2){block}, it will be transformed into s while(exp){block;exp2};

If the statement is printf("parameter", exp), it will be converted to output(exp);

If the statement is scanf("parameter", exp), it will be converted to input(exp);

Among them, the conversion rules for the IF statement are as follows:

If the statement is in the form of if(exp)s, it is transformed into if(exp)then{s}

If the statement is in the form of if(exp){block}, it will be converted into if(exp)then{s}

If the statement is in the form of if(exp){block1}else{block2}, it is transformed into if(exp)then{block1}else{block2}

If the statement is in the form of if(exp1){block1}else if(exp2){block2}, it is converted into if(exp1)then{block1}else if(exp2){block2}

Assuming that var_list represents a column of variables connected with ",", exp_list represents a column of expressions connected with ",", and ei is a symbol that appears in exp_list, the conversion rules of the declaration statement are as follows:

If the declaration statement is int x, convert it to int x;

If the declaration statement is int var_list, convert it to int var_list;

If the declaration statement is int x=exp, convert it to int x;x=exp and skip;

If the declaration statement is int exp_list, use the rules of the declaration statement to convert each expression in it into the corresponding independent MSVL declaration language.

On the basis of the above technical solution, the conversion rule of the basic sentence is for the conversion of the sentence block, and each basic sentence is transformed one by one until all the sentences in the sentence block are transformed.

Compared with the prior art, the present invention can realize the conversion of C program by converting C language into MSVL language and defining the conversion of basic sentences, and the obtained equivalent MSVL language can also be executed to obtain the simulation result of C program. The properties that need to be verified can be expressed by propositional logic of MSVL, and the C program is converted into an MSVL program. Therefore, the model construction and property description use the same language, so that modeling and verification can be carried out under the same logical framework, which can be easily realized Model checking for C language programs. The logic basis of MSVL's modeling and model checking method is the sequential logic belonging to the formal method, and the non-formal C language program is reformed to use the formal method to check its model, which ensures that the model built by the C program is accurate. Validity and reliability of verification and testing. After the program is written in the familiar C language, it can be model-checked with a formal language to ensure the safety and reliability of the program.

Description of drawings

Fig. 1 is a flow frame diagram of the present invention for C language program model detection.

Detailed ways

The invention provides a computer language conversion system, which can convert C language into MSVL language to detect programs in C language. It specifically includes, a computer language conversion system, which is used to convert a C language program into an MSVL language program, including a lexical analysis module, which converts a character sequence into a word sequence, and the character sequence includes a key word in the C language. Definition of words, identifiers, constants, operators, header files and comment lines; also includes a syntax analysis module, which identifies specific statements in the C language based on the relevant lexical rules of the C language specified in yacc; It also includes a conversion processing module, which converts the C language into the MSVL language according to the language conversion rules between the C language and the MSVL language.

Please refer to Fig. 1, introduce the method that uses computer language conversion system of the present invention to convert C language into MSVL language below.

The first step: the C language program is imported into the lexical analysis module, and this step includes converting the character sequence into a word sequence, and the character sequence includes keywords, identifiers, constants, operators, header files and comment lines in the C language definition.

After lexical analysis, the program becomes a sequence of keywords, constants, identifiers, and operators. Among them, the header file part and comment part in the C language program will be ignored after identification and will not be sent to the next module. In the above C language source program for finding the greatest common divisor and least common multiple, the lexical analysis rules used are:

1. When encountering the #include<stdio.h> statement in the header file, do nothing;

2. When a keyword is encountered, the tag name is returned, such as int returns INT, main returns MAIN;

3. When encountering an identifier, return the token to the Yacc parser, such as num1, num2, a, etc.;

4. When an operator is encountered, return the tag name of the operator, such as !=, =, %, *, etc.;

5. If a space is encountered, it is ignored and no action is taken.

So far, through the definition of lexical rules, the function of using lex lexical analysis to perform lexical analysis on programs in the source language C language has been realized.

Step 2: import the word flow obtained in step 1 into the grammar analysis module, this step includes identifying specific sentences in C language based on the relevant lexical rules of C language specified in yacc.

As shown in Figure 2, the lex lexical analyzer is used to perform lexical analysis on the input C program, and the generated word flow and token flow are used as the input of the yacc grammatical analyzer. Rules, and then identify specific statements, which are: basic expression statements (such as a<b), while statements and if statements, and statement blocks in if statements and while statements.

The third step: convert the C language statement sequence identified by the second step grammatical analysis into a corresponding MSVL statement in the conversion processing module according to the corresponding conversion rules;

Step 4: Connect the obtained MSVL statement sequence with the sequence operator ";" to obtain the MSVL program.

The structured statements in the C language described in the syntax analysis module include basic expression statements, while statements, if statements, if-else statements, for statements, switch statements, printf statements and scanf statements.

The while statement, the loop body part of the for statement, the if statement, and the conditional statement part of the if-else statement in the structured statement in the C language described in the syntax analysis module are regarded as a statement block.

Defining conversion rules includes defining pair expression conversion rules, sentence conversion rules and statement block conversion rules.

On the basis of the above-mentioned technical scheme, the transformation rule of described expression is as follows:

Convert the expression, assuming that x and y are standard symbols, and e represents a constant or variable, the reference rules are as follows:

If the expression is e, convert it to MSVL expression and return e;

If the expression is [x++|x--], it will be transformed into MSVL statement x:=x+1and skip or x:=x-1and skip;

If the expression is x=y, it will be transformed into MSVL statement x:=y and skip;

If the expression is x==y, it will be transformed into MSVL statement x==y;

If the expression is x[+,-,*,/,%,!=]y, it will be converted to MSVL expression x[+,-,*,/,%,!=]y;

If the expression is x*=y(*=[<|>]), it will be converted to MSVL expression x=y or x*y;

If the expression is x[+|-|*|/|%]=y, it is transformed into x:=x[+|-|*|/|%]y and skip;

If the expression is x&&y, it will be transformed into MSVL statement x and skip;

If the expression is x||y, it is transformed into the MSVL statement x or y;

If the expression is x, y, it will be converted into MSVL statement x, y;

If the expression is (x), it is converted into an MSVL statement as (x);

The following describes the statement conversion rules and statement block conversion rules to convert basic statements. Basic statements include statements and statement blocks. Assume that exp is a constant expression, block is a statement block, s represents a complete statement, and x is a variable. , parameter represents a string, and the rules are as follows:

If the statement is an empty statement, convert it to an empty statement;

If the statement is exp, convert it to exp;

If the statement is x=exp, it is transformed into x:=exp and skip;

If the statement is an if statement, use the conversion rules of the IF statement to convert the statement;

If the statement is while(exp){block}, it is converted into MSVL statement while(exp){block};

If the statement is an int declaration statement, use the conversion rules of the declaration statement to convert the statement;

If the statement is for(s exp1;exp2){block}, it is transformed into s while(exp){block;exp2};

If the statement is printf("parameter", exp), it will be converted to output(exp);

If the statement is scanf("parameter", exp), it is converted to input(exp);

Among them, the conversion rules for the IF statement are as follows:

If the statement is in the form of if(exp)s, it is transformed into if(exp)then{s}

If the statement is in the form of if(exp){block}, it will be converted into if(exp)then{s}

If the statement is in the form of if(exp){block1}else{block2}, it is transformed into if(exp)then{block1}else{block2}

If the statement is in the form of if(exp1){block1}else if(exp2){block2}, it is converted into if(exp1)then{block1}else if(exp2){block2}

Assuming that var_list represents a column of variables connected with ",", exp_list represents a column of expressions connected with ",", and ei is a symbol that appears in exp_list, the conversion rules of the declaration statement are as follows:

If the declaration statement is int x, convert it to int x;

If the declaration statement is int var_list, convert it to int var_list;

If the declaration statement is int x=exp, convert it to int x;x=exp and skip;

If the declaration statement is int exp_list, use the rules of the declaration statement to convert each expression in it, and convert them into corresponding independent MSVL declaration statements.

The conversion rules of the basic sentence are for the conversion of the statement block, and each basic statement is converted one by one until all the statements in the statement block are converted.

Claims (8)

1. A computer language conversion system, which is used to convert a C language program into an MSVL language program, is characterized in that: it includes, A lexical analysis module, which converts the character sequence into a word sequence, and the character sequence includes definitions of keywords, identifiers, constants, operators, header files and comment lines in the C language; The grammatical analysis module, which is based on the relevant lexical rules of the C language specified in yacc, and then identifies specific sentences in the C language; The conversion processing module converts the C language into the MSVL language according to the language conversion rule between the C language and the MSVL language. 2. a conversion method from C language to MSVL language, it provides lexical analysis module, syntax analysis module and conversion processing module, it is characterized in that: described method comprises the following steps; The first step: the C language program is imported into the lexical analysis module, and this step includes converting the character sequence into a word sequence, and the character sequence includes keywords, identifiers, constants, operators, header files and comment lines in the C language definition; Step 2: import the word stream obtained in step 1 into the syntax analysis module, which step includes identifying specific sentences in the C language based on the relevant lexical rules of the C language specified in the yacc; The third step: convert the C language statement sequence identified by the second step grammatical analysis into a corresponding MSVL statement in the conversion processing module according to the corresponding conversion rules; Step 4: Connect the obtained MSVL statement sequence with the sequence operator ";" to obtain the MSVL program. 3. a kind of C language according to claim 2 is to the conversion method of MSVL language, it is characterized in that: the structured statement in the C language described in the syntax analysis module comprises basic expression statement, while statement, if statement, if-else statement, for statement, switch statement, printf statement, and scanf statement. 4. a kind of C language according to claim 2 is to the conversion method of MSVL language, it is characterized in that: the while statement of structured statement in the C language described in the described syntax analysis module, the cycle body part of for statement and The conditional statement of the if statement and if-else statement is a statement block. 5. a kind of C language according to claim 1 is to the conversion method of MSVL language, it is characterized in that: the language conversion rule between described C language and MSVL language comprises expression conversion rule, sentence conversion rule and sentence block conversion rule. 6. a kind of C language according to claim 5 is to the conversion method of MSVL language, it is characterized in that: the conversion rule of described expression is as follows: Convert the expression, assuming that x and y are standard symbols, and e represents a constant or variable, the reference rules are as follows: If the expression is e, convert it to MSVL expression and return e; If the expression is [x++|x--], it is transformed into the MSVL statement x:=x+1and skip or x:=x-1and skip; If the expression is x=y, it is transformed into the MSVL statement x:=y and skip; If the expression is x==y, it will be transformed into MSVL statement x==y; If the expression is x[+,-,*,/,%,!=]y, it will be converted to MSVL expression x[+,-,*,/,%,!=]y; If the expression is x*=y(*=[<|>]), convert to MSVL expression x=y or x*y; If the expression is x[+|-|*|/|%]=y, convert to x:=x[+|-|*|/|%]y and skip; If the expression is x&&y, it will be converted into MSVL statement x and skip; If the expression is x||y, it is converted into the MSVL statement x or y; If the expression is x, y, it will be converted into MSVL statement x, y; If the expression is (x), it will be converted to MSVL statement as (x). 7. a kind of C language as claimed in claim 5 is to the conversion method of MSVL language, it is characterized in that: described sentence conversion rule and sentence block conversion rule are as follows, To convert the basic statement, assuming that exp is a constant expression, block is a statement block, s represents a complete statement, x is a variable, and parameter represents a string, the rules are as follows: If the statement is, transformed into; If the statement is exp, convert it to exp; If the statement is x=exp, it is transformed into x:=exp and skip; If the statement is an if statement, use the conversion rules of the IF statement to convert the statement; If the statement is while(exp){block}, it is converted into MSVL statement while(exp){block}; If the statement is an int declaration statement, use the conversion rules of the declaration statement to convert the statement; If the statement is for(s exp1;exp2){block}, it is transformed into s while(exp){block}; If the statement is printf("parameter", exp), it will be converted to output(exp); If the statement is scanf("parameter", exp), it is converted to input(exp); Among them, the conversion rules for the IF statement are as follows: If the statement is in the form of if(exp)s, it is transformed into if(exp)then{s} If the statement is in the form of if(exp){block}, it will be converted into if(exp)then{s} If the statement is in the form of if(exp){block1}else{block2}, it is transformed into if(exp)then{block1}else{block2} If the statement is if(exp1){block1}else if(exp2){block2}, it will be converted into if(exp1)then{block1}else if(exp2){block2} Assuming that var_list represents a column of variables connected with ",", exp_list represents a column of expressions connected with ",", and ei is a symbol that appears in exp_list, the conversion rules of the declaration statement are as follows: If the declaration statement is int x, convert it to int x; If the declaration statement is int var_list, convert it to int var_list; If the declaration statement is int x=exp, convert it to int x;x=exp and skip; If the declaration statement is int exp_list, use the rules of the declaration statement to convert each expression in it into the corresponding independent MSVL declaration language. 8. a kind of C language according to claim 5 is to the conversion method of MSVL language, it is characterized in that: the conversion rule of described basic sentence is for the transformation of sentence block, and each basic sentence is converted one by one respectively, until sentence All statements in the block are converted.