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jlemon

A fork of the LEMON parser generator that generates Java code and the associated SQL parser.

Files lemon.c, lempar.c are extracted from SQLite v3.18.0.

Maven Central Javadocs

Usage

> # compile
> cc -g -O2 -o jlemon lemon.c
> # run
> jlemon <filename>.y
> # preprocess generated code
> cpp -P <filename>.j > yyParser.java

For example:

cc -g -O2 -o jlemon lemon.c
./jlemon src/test/java/simple/parser.y
cpp -P src/test/java/simple/parser.j > src/test/java/simple/yyParser.java
mvn test

Or on Windows platform:

cl /O2 /Fejlemon.exe lemon.c
jlemon.exe src\test\java\simple\parser.y
cl /EP /C src\test\java\simple\parser.j > src\test\java\simple\yyParser.java

Generated Parser API

public class yyParser {
  // %extra_argument declaration

  public yyParser(
    ParseARG_PDECL               /* Optional %extra_argument parameter */
  ) {
    // constructor
  }
  public void ParseFinalize() {  /* or can be renamed to %nameFinalize */
    // optional (clean the stack)
  }
  public void Parse(             /* or can be renamed to %name */
    int yymajor,                 /* The major token code number */
    ParseTOKENTYPE yyminor       /* The value for the token */
  ){
    // To be called by lexer
  }
}

Hack

As there is no union in Java, yy%d fields of YYMINORTYPE have been replaced by yy%d() getters and yy%d(%type value) setters. But when translating code (see translate_code), the logic used to make the difference between a read access to a yy%d field and a write access is fallible.

Maybe try a code manipulator (janino) ? Or javolution Union ?

SQL Parser

SQLite lexer and SQLite parser have been ported from C to Java. The parser generates an AST.

The parser is/will be used to fix DatabaseMetaData implementation.

  • java.sql.DatabaseMetaData.getColumns
  • java.sql.DatabaseMetaData.getPrimaryKeys
  • java.sql.DatabaseMetaData.getBestRowIdentifier
  • java.sql.DatabaseMetaData.getCrossReference
  • java.sql.DatabaseMetaData.getImportedKeys
  • java.sql.DatabaseMetaData.getExportedKeys
  • java.sql.DatabaseMetaData.getIndexInfo

Lexer/Parser

  • Keep track of position (line, column).
  • Streamable (stop at the end of statement).
  • Resumable (restart after the end of statement).

Test

SQL lexer and parser have been tested with the following scripts: