ref: 068f403e7111016383f65b46eeffd5ae592964f2
dir: /sys/src/cmd/grap/for.c/
#include <stdio.h> #include <stdlib.h> #include "grap.h" #include "y.tab.h" typedef struct { Obj *var; /* index variable */ double to; /* limit */ double by; int op; /* operator */ char *str; /* string to push back */ } For; #define MAXFOR 10 For forstk[MAXFOR]; /* stack of for loops */ For *forp = forstk; /* pointer to current top */ void forloop(Obj *var, double from, double to, int op, double by, char *str) /* set up a for loop */ { fprintf(tfd, "# for %s from %g to %g by %c %g \n", var->name, from, to, op, by); if (++forp >= forstk+MAXFOR) ERROR "for loop nested too deep" FATAL; forp->var = var; forp->to = to; forp->op = op; forp->by = by; forp->str = str; setvar(var, from); nextfor(); unput('\n'); } void nextfor(void) /* do one iteration of a for loop */ { /* BUG: this should depend on op and direction */ if (forp->var->fval > SLOP * forp->to) { /* loop is done */ free(forp->str); if (--forp < forstk) ERROR "forstk popped too far" FATAL; } else { /* another iteration */ pushsrc(String, "\nEndfor\n"); pushsrc(String, forp->str); } } void endfor(void) /* end one iteration of for loop */ { switch (forp->op) { case '+': case ' ': forp->var->fval += forp->by; break; case '-': forp->var->fval -= forp->by; break; case '*': forp->var->fval *= forp->by; break; case '/': forp->var->fval /= forp->by; break; } nextfor(); } char *ifstat(double expr, char *thenpart, char *elsepart) { dprintf("if %g then <%s> else <%s>\n", expr, thenpart, elsepart? elsepart : ""); if (expr) { unput('\n'); pushsrc(Free, thenpart); pushsrc(String, thenpart); unput('\n'); if (elsepart) free(elsepart); return thenpart; /* to be freed later */ } else { free(thenpart); if (elsepart) { unput('\n'); pushsrc(Free, elsepart); pushsrc(String, elsepart); unput('\n'); } return elsepart; } }