Reference

sglr-api(3)

SGinitParser, SGopenLanguageFromTerm, SGopenLanguage, SGcloseLanguage, SGreOpenLanguage, SGparseString, SGparseStringAsAsFix2, SGparseStringAsAsFix1, SGparseFile, SGtermToFile, SGparseFileUsingTable, SGisParseTree, SGisParseError - an interface to the Scannerless Generalized LR parser SGLR library (libsglr, -lsglr)
Definitions

API Functions














Operating Mode Macros












The SGLR API offers high-level support for parsing functionality. A few key concepts: in order to parse an input term, a parse table for the language in which the term is supposed to be written must be present. A database of parse tables is maintained for that purpose. In general, the user first makes sure the appropriate parse table for some language L is opened; after that, terms can be parsed over that language L. As a result, either a parse error or a parse forest will be returned. Parse forests can be written to a file. The functions in the API that return an ATerm will return NULL on an operational error; bear in mind that a successful parse that stumbles upon a syntax error in the input term will produce an error term rather than NULL. Functions for checking parse results are therefore also provided. Throughout the interface, a errpre argument specifies a prefix that is used in contexts where an error message is returned to the user. It is typically instantiated with the toolname, making it possible to identify the source of any occurring error message in a possibly complex toolchain.
API Functions

If a parse table of the indicated name is already present, the existing table will be used. The SGreOpenlanguage, used identically to SGopenlanguage, replaces eventually existing parse tables by the table contained in the named file.


For SGparseFile, the term contained in named input file infil is parsed over the parse table as previously opened and registered by the name lang.

SGparseFileUsingTable uses a parse table contained in tblfil to parse the term contained in the named file infil, and writes output to the named file outfil.


Operating Mode Macros A number of macros influence the parsing process. The following naming convention is used: use SG_XXX as a variable to check whether option XXX is enabled; use SG_XXX_ON() to enable and SG_XXX_OFF() to enable or disable option XXX, respectively.






These specific toggles are supposed to be used for debugging purposes only. So, do not use these options to tweak your language implementations! It is highly probable that there will be no backward compatibility for them in future versions.

  #include <sglr.h>


  #define ME "MyParser"
  #define L  "MyLanguageReferenceName"


  int main(int argc, char **argv)
  {
    ATerm bottomOfStack;
    ATerm forest;


    if(argc != 4) exit(1);


    ATinit(0, NULL, &bottomOfStack);


    SGinitParser(ATfalse);


    if(!SGopenLanguage(ME, L, argv[1])) {
      fprintf(stderr, "error opening language %s (in %s)\n", L, argv[1]);
      exit(2);
    }
    if(!(forest = SGparseFile(ME, L, NULL, argv[2]))) {
      fprintf(stderr, "error parsing %s (over %s)\n", argv[2], L);
      exit(3);
    }


    fprintf(stdout, "Parse successful, writing %s\n", argv[3]);
    SG_BINARY_OFF();  /*  Make output to `-' (stdout) safe  */
    SGtermToFile(ME, forest, argv[3]);
    return 0;
  }

the sglr manpage, the tree2dot manpage None. Jeroen Scheerder <[email protected]>