bc: Unwind the stack in every return - sbase - suckless unix tools
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---
(DIR) commit 98923f69a1bb852d7fcbf2146dec4a084874bf80
(DIR) parent 6edcf9948848793f67f04458a72c7825fe9e4138
(HTM) Author: Roberto E. Vargas Caballero <k0ga@shike2.net>
Date: Fri, 28 Nov 2025 12:34:55 +0100
bc: Unwind the stack in every return
When we return from a function we have to unwind the stack and
pop all the locals of that function. That requires to create
a string with all the pop information to be used in every return.
Diffstat:
M bc.y | 73 ++++++++++++++++++++++---------
1 file changed, 52 insertions(+), 21 deletions(-)
---
(DIR) diff --git a/bc.y b/bc.y
@@ -49,7 +49,7 @@ static char *var(char *);
static char *ary(char *);
static void writeout(char *);
-static char *yytext, *buff;
+static char *yytext, *buff, *unwind;
static char *filename;
static FILE *filep;
static int lineno, nerr, flowid;
@@ -158,29 +158,29 @@ for : FOR {$$ = macro(LOOP);}
def : DEF ID {$$ = macro(DEF);}
;
-parlst : '(' ')' {$$ = code("%%s");}
+parlst : '(' ')' {$$ = code("");}
| '(' params ')' {$$ = $2;}
;
-params : param
- | params ',' param {$$ = code($1, $3); free($1);}
+params : param {$$ = param(NULL, $1);}
+ | params ',' param {$$ = param($1, $3);}
;
-param : ID {$$ = code("S%s%%sL%ss.", var($1), var($1));}
- | ID '[' ']' {$$ = code("S%s%%sL%ss.", ary($1), ary($1));}
+param : ID {$$ = var($1);}
+ | ID '[' ']' {$$ = ary($1);}
;
-autolst : {$$ = code("%%s");}
+autolst : {$$ = code("");}
| AUTO locals '\n' {$$ = $2;}
| AUTO locals ';' {$$ = $2;}
;
-locals : local
- | locals ',' local {$$ = code($1, $3); free($1);}
+locals : local {$$ = local(NULL, $1);}
+ | locals ',' local {$$ = local($1, $3);}
;
-local : ID {$$ = code("0S%s%%sL%ss.", var($1), var($1));}
- | ID '[' ']' {$$ = code("0S%s%%sL%ss.", ary($1), ary($1));}
+local : ID {$$ = var($1);}
+ | ID '[' ']' {$$ = ary($1);}
;
arglst : expr
@@ -379,19 +379,50 @@ macro(int op)
}
static char *
-funcode(Macro *d, char *params, char *vars, char *body)
+param(char *list, char *id)
+{
+ char *i1, *i2;
+
+ i1 = estrdup(id);
+ i2 = estrdup(id);
+ free(id);
+
+ unwind = code(unwind ? "L%ss.%s" : "L%ss.", i1, unwind);
+
+ return code(list ? "S%s%s" : "S%s" , i2, list);
+}
+
+static char *
+local(char *list, char *id)
{
- char *s, *t1, *t2;
+ char *i1, *i2;
- t1 = code(vars, params);
- t2 = code(t1, body);
+ i1 = estrdup(id);
+ i2 = estrdup(id);
+ free(id);
+ unwind = code(unwind ? "L%ss.%s" : "L%ss.", i1, unwind);
+
+ return code(list ? "0S%s%s" : "0S%s" , i2, list);
+}
+
+static char *
+funcode(Macro *d, char *params, char *vars, char *body)
+{
+ char *s;
+
+ s = code("[%s%s%s%s]s%c",
+ vars, params,
+ body,
+ retcode(code(" 0")),
+ d->id);
+ free(unwind);
+ unwind = NULL;
nested--;
inhome = 0;
- free(vars);
- free(t1);
- return code("[%s 0 1Q]s%c", t2, d->id);
+
+ return s;
}
static char *
@@ -415,7 +446,7 @@ forcode(Macro *d, char *init, char *cmp, char *inc, char *body)
body,
inc,
estrdup(cmp),
- d->flowid, d->id);
+ d->id, d->id);
writeout(s);
s = code("%ss.%s%c", init, cmp, d->id);
@@ -432,7 +463,7 @@ whilecode(Macro *d, char *cmp, char *body)
s = code("[%ss.%s%c]s%c",
body,
estrdup(cmp),
- d->flowid, d->id);
+ d->id, d->id);
writeout(s);
s = code("%s%c", cmp, d->id);
@@ -462,7 +493,7 @@ retcode(char *expr)
if (nested < 2 || macros[1].op != DEF)
yyerror("return must be in a function");
- return code("%s %dQ", expr, nested - 1);
+ return code("%s %s %dQ", estrdup(unwind), expr, nested - 1);
}
static char *