commit 721e8bb7e608fdadebbb780bfde127a699e3bc5c
parent e656b3773023a7a1c60d0573bb326e40d450e8cc
Author: Roberto E. Vargas Caballero <k0ga@shike2.net>
Date: Tue, 25 Nov 2025 10:31:11 +0100
bc: Rewrite macros to implement break and return
The macros as implemented didn't allow correct tracking of the control
flow structures, and knowing he nesting level for return or break was
difficult. The tokens IF, WHILE and FOR were redirected to on terminal
symbols to be sure that the macro was already pushed before the rest
of the statement was parsed (including the global nested).
Diffstat:
| M | bc.y | | | 225 | ++++++++++++++++++++++++++++++++++++++++++------------------------------------- |
1 file changed, 119 insertions(+), 106 deletions(-)
diff --git a/bc.y b/bc.y
@@ -17,17 +17,17 @@
#define DIGITS "0123456789ABCDEF"
#define NESTED_MAX 10
+#define funid(f) ((f)[0] - 'a' + 1)
+
int yydebug;
typedef struct macro Macro;
struct macro {
- char *init;
- char *cmp;
- char *inc;
- char *vars;
- char *body;
- int n;
+ int op;
+ int id;
+ int flowid;
+ int nested;
};
static int yyerror(char *);
@@ -35,12 +35,14 @@ static int yylex(void);
static void quit(void);
static char *code(char *, ...);
-static char *forcode(Macro *, char *);
-static char *whilecode(Macro *, char *);
-static char *ifcode(Macro *, char *);
-static char *funcode(Macro *, char *, char *);
-static Macro *macro(char *, char *, char *);
-static Macro *function(char *, char *);
+static char *forcode(Macro *, char *, char *, char *, char *);
+static char *whilecode(Macro *, char *, char *);
+static char *ifcode(Macro *, char *, char *);
+static char *funcode(Macro *, char *, char *, char *);
+static Macro *define(char *, char *);
+static char *retcode(char *);
+static char *brkcode(void);
+static Macro *macro(int, int);
static char *ftn(char *);
static char *var(char *);
@@ -67,6 +69,7 @@ int cflag, dflag, lflag, sflag;
%token <id> ID
%token <str> STRING NUMBER
%token <str> EQOP '+' '-' '*' '/' '%' '^' INCDEC
+%token HOME LOOP
%token EQ
%token LE
%token GE
@@ -85,11 +88,10 @@ int cflag, dflag, lflag, sflag;
%token OBASE
%token AUTO
-%type <str> assign nexpr expr exprstat rel stat ary statlst
-%type <str> autolst arglst
-%type <str> parlst locals local
-%type <str> function
-%type <macro> fordef cond funbody
+%type <str> assign nexpr expr exprstat rel stat ary statlst cond
+%type <str> autolst arglst parlst
+%type <str> params param locals local
+%type <macro> def if for while
%right '=' EQOP
%left '+' '-'
@@ -101,11 +103,11 @@ int cflag, dflag, lflag, sflag;
%%
program :
- | item program
+ | item program {used = 0;}
;
-item : scolonlst '\n' {used = 0;}
- | function {writeout($1); used = 0;}
+item : scolonlst '\n'
+ | def parlst '{' '\n' autolst statlst '}' {funcode($1, $2, $5, $6);}
;
scolonlst:
@@ -124,31 +126,39 @@ statlst : {$$ = code("");}
stat : exprstat
| STRING {$$ = code("[%s]P", $1);}
- | BREAK {$$ = code(" %dQ", nested);} /* FIXME */
+ | BREAK {$$ = brkcode();}
| QUIT {quit();}
- | RETURN {$$ = code(" %dQ", nested);}
- | RETURN '(' expr ')' {$$ = code(" %s %dQ", $3, nested);}
- | RETURN '(' ')' {$$ = code(" %dQ", nested);}
- | FOR fordef stat {$$ = forcode($2, $3);}
- | IF cond stat {$$ = ifcode($2, $3);}
- | WHILE cond stat {$$ = whilecode($2, $3);}
+ | RETURN {$$ = retcode("0");}
+ | RETURN '(' expr ')' {$$ = retcode($3);}
+ | RETURN '(' ')' {$$ = retcode("0");}
+ | while cond stat {$$ = whilecode($1, $2, $3);}
+ | if cond stat {$$ = ifcode($1, $2, $3);}
| '{' statlst '}' {$$ = $2;}
+ | for '(' expr ';' rel ';' expr ')' stat {$$ = forcode($1, $3, $5, $7, $9);}
;
-fordef : '(' expr ';' rel ';' expr ')' {$$ = macro($2, $4, $6);}
+while : WHILE {$$ = macro(LOOP, 0);}
;
-cond : '(' rel ')' {$$ = macro(NULL, $2, NULL);}
+if : IF {$$ = macro(IF, 0);}
;
-function: DEF ID parlst funbody {$$ = funcode($4, $2, $3);}
+for : FOR {$$ = macro(LOOP, 0);}
;
-funbody : '{' '\n' autolst statlst '}' {$$ = function($3, $4);}
+def : DEF ID {$$ = macro(DEF, funid($2));}
;
parlst : '(' ')' {$$ = "%s";}
- | '(' locals ')' {$$ = $2;}
+ | '(' params ')' {$$ = $2;}
+ ;
+
+params : param
+ | params ',' param {$$ = code("%s%s", $1, $3);}
+ ;
+
+param : ID {$$ = code("S%s%%sL%ss.", var($1), var($1));}
+ | ID '[' ']' {$$ = code("S%s%%sL%ss.", ary($1), ary($1));}
;
autolst : {$$ = "%s";}
@@ -160,8 +170,8 @@ locals : local
| locals ',' local {$$ = code("%s%s", $1, $3);}
;
-local : ID {$$ = code("S%s%%sL%ss.", var($1), var($1));}
- | ID '[' ']' {$$ = code("S%s%%sL%ss.", ary($1), ary($1));}
+local : ID {$$ = code("0S%s%%sL%ss.", var($1), var($1));}
+ | ID '[' ']' {$$ = code("0S%s%%sL%ss.", ary($1), ary($1));}
;
arglst : expr
@@ -170,7 +180,10 @@ arglst : expr
| ID '[' ']' ',' arglst {$$ = code("%s%s", ary($1), $5);}
;
-rel : expr
+cond : '(' rel ')' {$$ = $2;}
+ ;
+
+rel : expr {$$ = code("%s 0!=", $1);}
| expr EQ expr {$$ = code("%s%s=", $3, $1);}
| expr LE expr {$$ = code("%s%s!>", $3, $1);}
| expr GE expr {$$ = code("%s%s!<", $3, $1);}
@@ -179,7 +192,7 @@ rel : expr
| expr '>' expr {$$ = code("%s%s>", $3, $1);}
;
-exprstat: nexpr {$$ = code("%s%s", $1, sflag ? "s." : "p");}
+exprstat: nexpr {$$ = code("%s%ss.", $1, sflag ? "" : "p");}
| assign {$$ = code("%ss.", $1);}
;
@@ -237,7 +250,7 @@ ary : '[' expr ']' {$$ = $2;}
static int
yyerror(char *s)
{
- fprintf(stderr, "bc: %s:%d:%s\n", filename, lineno, s);
+ fprintf(stderr, "bc: %s:%d: %s\n", filename, lineno, s);
nerr++;
longjmp(recover, 1);
}
@@ -276,91 +289,103 @@ code(char *fmt, ...)
return s;
}
-static char *
-funcode(Macro *d, char *id, char *params)
+static Macro *
+macro(int op, int id)
{
- char *s;
+ Macro *d;
- s = code(d->vars, d->body);
- s = code(params, s);
- s = code("[%s]s%s", s, id);
- return s;
+ if (nested == NESTED_MAX)
+ yyerror("too much nesting");
+
+ d = ¯os[nested];
+ d->flowid = (op == HOME) ? '0' - 1: d[-1].flowid + 1;
+ d->id = (id != 0) ? id : d->flowid;
+ d->op = op;
+ d->nested = nested++;
+
+ return d;
}
static char *
-forcode(Macro *d, char *body)
+funcode(Macro *d, char *params, char *vars, char *body)
{
char *s;
- s = code("[%s%ss.%s%d]s%d",
- body,
- d->inc,
- d->cmp,
- d->n, d->n);
- writeout(s);
-
- s = code("%ss.l%dx", d->init, d->n);
+ s = code(vars, params);
+ s = code(s, body);
+ s = code("[%s 0 1Q]s%c", s, d->id);
nested--;
+ writeout(s);
return s;
}
static char *
-whilecode(Macro *d, char *body)
+brkcode(void)
+{
+ Macro *d;
+
+ for (d = ¯os[nested-1]; d->op != HOME && d->op != LOOP; --d)
+ ;
+ if (d->op == HOME)
+ yyerror("break not in for or while");
+ return code(" %dQ", nested - d->nested);
+}
+
+static char *
+forcode(Macro *d, char *init, char *cmp, char *inc, char *body)
{
char *s;
- s = code("[%ss.%s%d]s%d", body, d->cmp, d->n, d->n);
+ s = code("[%s%ss.%s%c]s%c",
+ body,
+ inc,
+ cmp,
+ d->flowid, d->flowid);
writeout(s);
- s = code("l%dx", d->n);
+ s = code("%ss.%s%c", init, cmp, d->flowid);
nested--;
return s;
}
static char *
-ifcode(Macro *d, char *body)
+whilecode(Macro *d, char *cmp, char *body)
{
char *s;
- s = code("[%s]s%d", body, d->n);
+ s = code("[%ss.%s%c]s%c", body, cmp, d->flowid, d->flowid);
writeout(s);
- s = code("%s%d", d->cmp, d->n);
+ s = code("%s%c", cmp, d->flowid);
nested--;
return s;
}
-static Macro *
-macro(char *init, char *cmp, char *inc)
+static char *
+ifcode(Macro *d, char *cmp, char *body)
{
- Macro *d;
+ char *s;
- if (nested == NESTED_MAX)
- yyerror("bc:too much nesting");
+ s = code("[%s]s%c", body, d->flowid);
+ writeout(s);
- d = ¯os[nested];
- d->init = init;
- d->cmp = cmp;
- d->inc = inc;
- d->n = nested++;
+ s = code("%s%c", cmp, d->flowid);
+ nested--;
- return d;
+ return s;
}
-static Macro *
-function(char *vars, char *body)
+static char *
+retcode(char *expr)
{
- Macro *d;
-
- assert(nested == 0);
- d = macro(NULL, NULL, NULL);
- d->vars = vars;
- d->body = body;
+ char *s;
- return d;
+ if (nested < 2 || macros[1].op != DEF)
+ yyerror("return must be in a function");
+ return code("%s %dQ", expr, nested - 1);
}
static char *
@@ -372,7 +397,7 @@ ary(char *s)
static char *
ftn(char *s)
{
- return code("%c", s[0] | 0x80);
+ return code("%c", funid(s));
}
static char *
@@ -502,7 +527,7 @@ end:
return NUMBER;
toolong:
- yyerror("bc:too long number");
+ yyerror("too long number");
}
static int
@@ -517,7 +542,7 @@ string(int ch)
}
if (bp == &yytext[BUFSIZ])
- yyerror("bc:too long string");
+ yyerror("too long string");
*bp = '\0';
yylval.str = yytext;
@@ -661,48 +686,31 @@ spawn(void)
}
}
-static void
-init(void)
-{
- used = 0;
-
- if (!yytext)
- yytext = malloc(BUFSIZ);
- if (!buff)
- buff = malloc(BUFSIZ);
- if (!yytext || !buff)
- eprintf("out of memory\n");
-}
-
static int
run(void)
{
- if (feof(stdin))
- return 0;
-
- if (setjmp(recover))
- return 1;
-
+ setjmp(recover);
yyparse();
- return 1;
}
static void
bc(char *fname)
{
+ Macro *d;
+
lineno = 1;
- nested = 0;
+ used = nested = 0;
+ macro(HOME, 0);
if (fname) {
filename = fname;
if (!freopen(fname, "r", stdin))
eprintf("%s:", fname);
}
- for (init(); run(); init())
- ;
- nested = used = 0;
+ run();
}
+
static void
loadlib(void)
{
@@ -765,6 +773,11 @@ main(int argc, char *argv[])
usage();
} ARGEND
+ yytext = malloc(BUFSIZ);
+ buff = malloc(BUFSIZ);
+ if (!yytext || !buff)
+ eprintf("out of memory\n");
+
if (!cflag)
spawn();
if (lflag)
