Parsing of declarations in all branches of preprocessor conditionals

• US 8,495,591 B2
• Filed: 12/12/2011
• Issued: 07/23/2013
• Est. Priority Date: 06/17/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Miceli, Thierry
• Primary Examiner(s): Das, Chameli
• Application Number:
  US13/316,678
• Publication Number:
  US 20120096446A1
• Time in Patent Office: 589 Days
• Field of Search: None
• US Class Current: 717/129
• CPC Class Codes: G06F 8/423 Preprocessors
• CPC Class Codes: G06F 8/427 Parsing

Abstract

Declarations from an input source code are serialized into a stream of tokens produced by following each branch of a preprocessor conditional directive statement that interrupts a declaration. Tokens are labeled with a parsing path indicator corresponding to a parsing path induced by branches of a preprocessor conditional directive. The declarations that are formed along the different parsing paths are serialized by fetching the tokens that belong to the first parsing path in a first pass, and passing the tokens on to a next phase of a compiler. The pointer that marks the next token is repositioned to return to the start of the declaration. The declaration may be serialized again through the second parsing path in a second pass. The operation may be repeated until each of the parsing paths induced by the presence of branches of the preprocessor conditional directives in the source code is exhausted.

Claims

1. A system that parses a plurality of preprocessor conditional branches of a preprocessor conditional directive statement comprising:

a computer comprising a processor and a memory, the computer further comprising;

a declaration serializer that, in order to have information available in each parsing path induced by mutually exclusive branches returned to a caller, serializes input into a stream of tokens produced by following each parsing path induced by mutually exclusive branches of a preprocessor conditional directive statement interrupting a declaration,

wherein the declaration serializer labels tokens belonging to a first parsing path with a first parsing path indicator,

wherein the declaration serializer labels tokens belonging to a second parsing path with a second parsing path indicator,

wherein the declaration serializer fetches the tokens that belong to the first parsing path in a first pass and returns the tokens that belong to the first parsing path to the caller and

wherein the declaration serializer fetches the tokens that belong to the second parsing path in a second pass and returns the tokens that belong to the second parsing path to the caller, wherein parsing paths induced by mutually exclusive branches of the preprocessor conditional directive statement are detected by matching preprocessor conditional directives of the preprocessor conditional directive statement.

2. The system of claim 1, wherein the caller comprises a compiler, a program development tool, a lexer, a syntax analyzer, a preprocessor or a preprocessor/lexer.

3. The system of claim 1, wherein a token buffer is generated by the declaration serializer, the token buffer comprising a plurality of tokens of the declaration, wherein each token of the plurality of tokens of the declaration is labeled with at least one parsing path indicator corresponding to a parsing path to which each token belongs.

4. The system of claim 1, wherein the declaration serializer returns tokens to the caller in the first pass wherein tokens labeled with the first parsing path indicator are processed and the second pass wherein tokens labeled with the second parsing path indicator are processed.

5. The system of claim 1, wherein the declaration serializer detects an interrupted declaration by detecting a beginning of declaration indicator, an end of declaration indicator and a preprocessor conditional directive between the beginning of declaration indicator and the end of declaration indicator.

6. The system of claim 5, wherein in response to detecting an end of declaration indicator, the declaration serializer returns to a beginning of the declaration and serializes tokens of a next parsing path.

7. A method of parsing a plurality of preprocessor conditional branches of a preprocessor conditional directive statement comprising:

using a processing unit, receiving an input from a caller, the input comprising the preprocessor conditional directive statement;

using the processing unit, in order to have information available in each parsing path induced by mutually exclusive branches returned to the caller, serializing the input into a stream of tokens produced by following each parsing path induced by mutually exclusive branches of the preprocessor conditional directive statement interrupting a declaration by;

labeling tokens belonging to a first parsing path with a first parsing path indicator;

labeling tokens belonging to a second parsing path with a second parsing path indicator;

fetching the tokens that belong to the first parsing path in a first pass and returning the tokens that belong to the first parsing path to the caller; and

fetching the tokens that belong to the second parsing path in a second pass and returning the tokens that belong to the second parsing path to the caller,

wherein parsing paths induced by mutually exclusive branches of the preprocessor conditional directive statement are detected by matching preprocessor conditional directives of the preprocessor conditional directive statement.

8. The method of claim 7, wherein the caller comprises a compiler, a program development tool, a lexer, a syntax analyzer, a preprocessor or a preprocessor/lexer.

9. The method of claim 7, further comprising generating a token buffer, the token buffer comprising a plurality of tokens of the declaration, wherein each token of the plurality of tokens of the declaration is labeled with at least one parsing path indicator corresponding to a parsing path to which each token belongs.

10. The method of claim 7, further comprising returning tokens to the caller in the first pass wherein tokens labeled with the first parsing path indicator are processed and the second pass wherein tokens labeled with the second parsing path indicator are processed.

11. The method of claim 7, further comprising detecting an interrupted declaration by detecting a beginning of declaration indicator, an end of declaration indicator and a preprocessor conditional directive between the beginning of declaration indicator and the end of declaration indicator.

12. The method of claim 11, wherein in response to detecting an end of declaration indicator, returning to a beginning of the declaration and serializes tokens of a next parsing path.

13. A computer-readable storage memory storing computer-executable instructions which when executed cause a computing environment to:

receiving an input from a caller, the input comprising the preprocessor conditional directive statement;

in order to have information available in each parsing path induced by mutually exclusive branches returned to the caller, serializing the input into a stream of tokens produced by following each parsing path induced by mutually exclusive branches of the preprocessor conditional directive statement interrupting a declaration by;

labeling tokens belonging to a first parsing path with a first parsing path indicator;

labeling tokens belonging to a second parsing path with a second parsing path indicator;

fetching the tokens that belong to the first parsing path in a first pass and returning the tokens that belong to the first parsing path to the caller; and

fetching the tokens that belong to the second parsing path in a second pass and returning the tokens that belong to the second parsing path to the caller,

wherein parsing paths induced by mutually exclusive branches of the preprocessor conditional directive statement are detected by matching preprocessor conditional directives of the preprocessor conditional directive statement.

14. The computer-readable storage memory of claim 13, wherein the caller comprises a compiler, a program development tool, a lexer, a syntax analyzer, a preprocessor or a preprocessor/lexer.

15. The computer-readable storage memory of claim 13, storing further computer-executable instructions, which when executed cause the computing environment to generate a token buffer, the token buffer comprising a plurality of tokens of the declaration, wherein each token of the plurality of tokens of the declaration is labeled with at least one parsing path indicator corresponding to a parsing path to which each token belongs.

16. The computer-readable storage memory of claim 13, storing further computer-executable instructions, which when executed cause the computing environment to return tokens to the caller in the first pass wherein tokens labeled with the first parsing path indicator are processed and the second pass wherein tokens labeled with the second parsing path indicator are processed.

17. The computer-readable storage memory of claim 13, storing further computer-executable instructions, which when executed cause the computing environment to detect an interrupted declaration by detecting a beginning of declaration indicator, an end of declaration indicator and a preprocessor conditional directive between the beginning of declaration indicator and the end of declaration indicator.