ING_DB
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Oliver Lehmann
parent
574f262941
commit
c2a6413e11
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/*
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** PARSER FOR YACC OUTPUT
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**
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** This is the same as the yacc parser found in the BS system
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** library "/lib/liby.a". There have been two kinds of
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** modifications. 1) The coding style has been altered to conform
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** to the DBS standard. 2) The changes marked by comments.
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*/
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# define MAXDEPTH 150
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extern char *yyval; /* defined in the table file */
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extern char *yylval; /* defined in the table file */
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extern char **yypv; /* defined in the table file */
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/* -------- the next line is an DBS customization -------- */
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int yypflag = 1; /* zero for no actions performed */
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int yydebug = 0; /* 1 for debugging */
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char *yyv[MAXDEPTH]; /* where the values are stored */
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int yystate = 0; /* current parser state */
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int yychar = -1; /* current input token number */
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int yynerrs = 0; /* number of errors */
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int yyerrflag = 0; /* error recovery flag */
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yyparse()
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{
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extern short yygo[];
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extern short yypgo[];
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extern short yyr1[];
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extern short yyr2[];
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extern short yyact[];
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extern short yypact[];
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/* DBS customization to make 'ps', 'p', and 'n' register variables */
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short s[MAXDEPTH];
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register short *ps;
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register short *p;
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register int n;
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register short ac;
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register int i;
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yystate = 0;
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yychar = -1;
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yynerrs = 0;
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yyerrflag = 0;
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ps = &s[0] - 1;
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yypv = &yyv[0] - 1;
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stack: /* put a state and value onto the stack */
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if (yydebug)
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printf("state %d value %d char %d\n", yystate, yyval, yychar);
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*++ps = yystate;
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*++yypv = yyval;
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newstate: /* set ap to point to the parsing actions for the new state */
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i = yypact[yystate + 1];
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p = &yyact[i];
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actn: /* get the next action, and perform it */
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n = (ac = *p++) & 07777; /* n is the "address" of the action */
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switch (ac >> 12) /* switch on operation */
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{
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case 1: /* skip on test */
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if (yychar < 0)
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{
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yychar = yylex();
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if (yydebug)
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printf( "character %d read\n", yychar );
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}
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/* ---------- the next 2 lines are an DBS customization ---------- */
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if (yychar < 0)
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return (1);
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if (n != yychar)
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p++;
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goto actn; /* get next action */
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case 2: /* shift */
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yystate = n;
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yyval = yylval;
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yychar = -1;
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if (yyerrflag)
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yyerrflag--;
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goto stack; /* stack new state */
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case 3: /* reduce */
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if (yydebug)
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printf("reduce %d\n", n);
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ps -= yyr2[n];
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yypv -= yyr2[n];
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yyval = yypv[1];
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/* -------- the next 2 lines are an DBS customization -------- */
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if (yypflag && yyactr(n))
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goto abort;
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/* consult goto table to find next state */
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i = yyr1[n];
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i = yypgo[i];
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p = &yygo[i];
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for ( ; *p != *ps && *p >= 0; p += 2)
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continue;
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yystate = p[1];
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goto stack; /* stack new state and value */
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case 4: /* accept */
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return (0);
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case 0: /* error ... attempt to resume parsing */
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switch (yyerrflag)
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{
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case 0: /* brand new error */
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/* ----------the next 2 lines are an DBS customization ---------- */
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/* syntax error */
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yyerror("syntax error");
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yynerrs++;
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case 1:
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case 2: /* incompletely recovered error ... try again */
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yyerrflag = 3;
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/* find a state where "error" is a legal shift action */
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while (ps >= s)
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{
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/* search ps actions */
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i = *ps;
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i = yypact[i + 1];
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p = &yyact[i];
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for ( ; (*p >> 12) == 1; p += 2)
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if (*p == 4352)
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goto found;
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/* the current ps has no shift onn "error", pop stack */
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if (yydebug)
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printf("err recov pops state %d, uncovers %d\n", ps[0], ps[-1]);
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ps--;
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yypv--;
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}
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/* there is no state on the stack with an error shift ... abort */
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abort:
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return (1);
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found: /* we have a state with a shift on "error", resume parsing */
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yystate = p[1] & 07777;
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goto stack;
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case 3: /* no shift yet; clobber input char */
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if (yydebug)
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printf("err recov discards char %d\n", yychar);
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/* don't discard EOF; quit */
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if (!yychar)
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goto abort;
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yychar = -1;
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goto newstate; /* try again in the same state */
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}
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}
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}
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