extern "C" {
#include <sglr.h>
#include <asfix2.h>
}

#include "parser.hh"
#include "shared.hh"
#include "expr.hh"
#include "parse-table.h"


Expr parseExprFromFile(const Path & path)
{
    /* Perhaps this is already an imploded parse tree? */
    Expr e = ATreadFromNamedFile(path.c_str());
    if (e) return e;

    /* Initialise the SDF libraries. */
    static bool initialised = false;
    static ATerm parseTable = 0;
    static language lang = 0;

    if (!initialised) {
        PT_initMEPTApi();
        PT_initAsFix2Api();
        SGinitParser(ATfalse);

        ATprotect(&parseTable);
        parseTable = ATreadFromBinaryString(
            (char *) fixParseTable, sizeof fixParseTable);
        if (!parseTable)
            throw Error(format("cannot construct parse table term"));

        ATprotect(&lang);
        lang = ATmake("Fix");
        if (!SGopenLanguageFromTerm(
                (char *) programId.c_str(), lang, parseTable))
            throw Error(format("cannot open language"));

        SG_STARTSYMBOL_ON();
        SG_OUTPUT_ON();
        SG_ASFIX2ME_ON();
        SG_AMBIGUITY_ERROR_ON();

        initialised = true;
    }

    ATerm result = SGparseFile((char *) programId.c_str(), lang,
        "Expr", (char *) path.c_str());
    if (!result)
        throw SysError(format("parse failed in `%1%'") % path);
    if (SGisParseError(result))
        throw Error(format("parse error in `%1%': %2%")
            % path % printTerm(result));

    PT_ParseTree tree = PT_makeParseTreeFromTerm(result);
    if (!tree)
        throw Error(format("cannot create parse tree"));
    
    ATerm imploded = PT_implodeParseTree(tree,
        ATtrue,
        ATtrue,
        ATtrue,
        ATtrue,
        ATtrue,
        ATtrue,
        ATfalse,
        ATtrue,
        ATtrue,
        ATtrue,
        ATfalse);
    if (!imploded)
        throw Error(format("cannot implode parse tree"));

    return imploded;
}