From 2ab912139deab6050cb70cbe25bcdb47727f56e5 Mon Sep 17 00:00:00 2001
From: Rodrigo Steinmuller Wanderley <rwanderley@dynavideo.com.br>
Date: Wed, 21 Nov 2007 17:04:10 -0300
Subject: [PATCH] Comecando a ficar mais com a cara de Yacc.

---
 exps/simples_fun.pl |   8 ++++
 parser.y            | 114 +++++++++++++++++++++++++++++-----------------------
 scanner.lex         |   4 +-
 vm.c                |   4 +-
 4 files changed, 75 insertions(+), 55 deletions(-)
 create mode 100644 exps/simples_fun.pl

diff --git a/exps/simples_fun.pl b/exps/simples_fun.pl
new file mode 100644
index 0000000..3818099
--- /dev/null
+++ b/exps/simples_fun.pl
@@ -0,0 +1,8 @@
+fun1 {
+  my $a;
+  $a = 2;
+}
+
+my $a;
+fun1(0, 1, $a);
+
diff --git a/parser.y b/parser.y
index cb7b01e..440869b 100644
--- a/parser.y
+++ b/parser.y
@@ -11,38 +11,37 @@
 
 #define YYDEBUG 1
 
-struct label {
-  char *id;
-  int for_goto;
-  int for_jmp_false;
-};
-
 void yyerror(char *);
 int yylex(void);
 int scope = 0;
-int nargs = 0;
-int fun_begin = 0;
 extern FILE *yyin;
-  
-struct label *
-alloc_label(void)
+
+void
+install(char *name)
 {
-  return calloc(1, sizeof(struct label));
+  symtab_t *node;
+
+  node = getsym(name, scope);
+  if (! node || node->scope < scope) {
+    node = putsym(name, scope, 0);
+  } else {
+    printf("%s jah estah definido neste escopo!\n", name);
+  }
 }
 
 void
-install(char *name)
+install_fun(char *name, int addr)
 {
   symtab_t *node;
 
   node = getsym(name, scope);
   if (! node || node->scope < scope) {
-    node = putsym(name, scope, gen_label());
+    node = putsym(name, scope, addr);
   } else {
     printf("%s jah estah definido neste escopo!\n", name);
   }
 }
-  
+
 void
 context_check(int op, char *name)
 {
@@ -65,26 +64,38 @@ call_fun(char *name)
   if (! id) {
     printf("Fuancao nao declarado: %s\n", name);
   } else {
-    /* id->addr points to the GOTO instruction */
-    gen_code(CALL, id->addr+1);
+    gen_code(CALL, id->addr);
   }
 }
 
 %}
 
 %union {
-  char *id;
   int ival;
-  struct label *label;
+  struct label {
+    int for_goto;
+    int for_jmp_false;
+  } label;
+  struct var {
+    char *id;
+  } var;
+  struct fun {
+    char *id;
+    int nargs;
+    int addr;
+  } fun;
 }
 
 %start program
 
 %token <ival> INTEGER
-%token <id> VARIABLE IDENTIFIER
+%token <fun> IDENTIFIER
+%token <var> VARIABLE
 %token <label> IF WHILE BREAK CONTINUE
 %token ELSIF ELSE MY WRT_INT RETURN
 
+%type <fun> fun_args fun_args_
+
 %right '='
 %left '+' '-'
 %left '*' '/' '%'
@@ -100,52 +111,54 @@ statements: statements statement
 ;
 
 statement: declarations ';'
-  |        VARIABLE '=' expression ';'      { context_check(STORE, $1); }
+  |        VARIABLE '=' expression ';'      { context_check(STORE, $1.id); }
   |        expression ';'
   |        WRT_INT '(' INTEGER ')' ';'      { gen_code(LOAD_INT, $3);
 	                                      gen_code(WRITE_INT, 0); }
-  |        WRT_INT '(' VARIABLE ')' ';'     { context_check(LOAD_VAR, $3);
+  |        WRT_INT '(' VARIABLE ')' ';'     { context_check(LOAD_VAR, $3.id);
 	                                      gen_code(WRITE_INT, 0); }
-  |        IF '(' expression ')' { $1 = alloc_label();
-                                   $1->for_jmp_false = reserve_loc(); }
+  |        IF '(' expression ')' { $1.for_jmp_false = reserve_loc(); }
            '{'                   { scope++; }
-           statements '}'    { scoperem(scope--);
-                               back_patch($1->for_jmp_false,
-					  JMP_FALSE,
-					  gen_label()); }
-  |        WHILE                 { $1 = alloc_label();
-                                   $1->for_goto = gen_label(); }
-           '(' expression ')'    { $1->for_jmp_false = reserve_loc(); }
+           statements '}'        { scoperem(scope--);
+                                   back_patch($1.for_jmp_false,
+					      JMP_FALSE,
+					      gen_label()); }
+  |        WHILE                 { $1.for_goto = gen_label(); }
+           '(' expression ')'    { $1.for_jmp_false = reserve_loc(); }
            '{'                   { scope++; }
            statements '}'        { scoperem(scope--);
-                                   gen_code(GOTO, $1->for_goto);
-			           back_patch($1->for_jmp_false,
+                                   gen_code(GOTO, $1.for_goto);
+			           back_patch($1.for_jmp_false,
 					      JMP_FALSE,
 					      gen_label()); }
-  |        IDENTIFIER            { install($1); 
-                                   fun_begin = reserve_loc();}
+  |        IDENTIFIER            { $1.addr = reserve_loc();}
            '{'                   { scope++; }
            statements '}'        { scoperem(scope--);
 	                           gen_code(RET, 0);
-	                           back_patch(fun_begin,
-                                   GOTO,
-                                   gen_label()); }
+	                           back_patch($1.addr++,
+					      GOTO,
+					      gen_label());
+	                           install_fun($1.id, $1.addr); }
 ;
 
-declarations: MY VARIABLE { install($2); }
+declarations: MY VARIABLE { install($2.id); }
   |           MY '(' id_list ')'
 ;
 
-id_list: id_list ',' VARIABLE { install($3); }
-  |      VARIABLE             { install($1); }
+id_list: id_list ',' VARIABLE { install($3.id); }
+  |      VARIABLE             { install($1.id); }
 ;
 
-fun_args_: fun_args | /* */ ;
+fun_args_: fun_args { $$ = $1; }
+  |        /* */    { $$.nargs = 0; }
+;
 
-fun_args: fun_args ',' INTEGER  { gen_code(LOAD_INT, $3); nargs++; }
-  |       fun_args ',' VARIABLE { context_check(LOAD_VAR, $3); nargs++; }
-  |       INTEGER               { gen_code(LOAD_INT, $1); nargs++; }
-  |       VARIABLE              { context_check(LOAD_VAR, $1); nargs++; }
+fun_args: fun_args ',' INTEGER  { gen_code(LOAD_INT, $3);
+                                  $$.nargs = $1.nargs + 1; }
+  |       fun_args ',' VARIABLE { context_check(LOAD_VAR, $3.id);
+                                  $$.nargs = $1.nargs + 1; }
+  |       INTEGER               { gen_code(LOAD_INT, $1); $$.nargs = 1; }
+  |       VARIABLE              { context_check(LOAD_VAR, $1.id); $$.nargs = 1; }
 ;
 
 expression: expression '+' expression { gen_code(ADD, 0); }
@@ -154,16 +167,15 @@ expression: expression '+' expression { gen_code(ADD, 0); }
   |         expression '/' expression { gen_code(DIV, 0); }
   |         expression '%' expression { gen_code(MOD, 0); }
   |         '(' expression ')'
-  |         IDENTIFIER '(' fun_args_ ')' { gen_code(PUSH_INT, nargs);
+  |         IDENTIFIER '(' fun_args_ ')' { gen_code(PUSH_INT, $3.nargs);
 	                                   /* +1: after load_int, +2: after call */
 	                                   gen_code(PUSH_INT, gen_label()+2);
-                                           nargs = 0;
-                                           call_fun($1); }
-  |         VARIABLE                  { context_check(LOAD_VAR, $1); }
+                                           call_fun($1.id); }
+  |         VARIABLE                  { context_check(LOAD_VAR, $1.id); }
   |         INTEGER                   { gen_code(LOAD_INT, $1); }
   |         RETURN INTEGER            { gen_code(LOAD_INT, $2);
                                         gen_code(RET, 0); }
-  |         RETURN VARIABLE           { context_check(LOAD_VAR, $2);
+  |         RETURN VARIABLE           { context_check(LOAD_VAR, $2.id);
                                         gen_code(RET, 0); }
 ;
 
diff --git a/scanner.lex b/scanner.lex
index cc1d3c3..81632ed 100644
--- a/scanner.lex
+++ b/scanner.lex
@@ -18,11 +18,11 @@
 "return" { return RETURN; }
 
 [a-zA-Z_][a-zA-Z0-9_]* {
-  yylval.id = strdup(yytext);
+  yylval.fun.id = strdup(yytext);
   return IDENTIFIER;
 }
 [$][a-zA-Z_][a-zA-Z0-9_]* {
-  yylval.id = strdup(yytext);
+  yylval.var.id = strdup(yytext);
   return VARIABLE;
 }
 [0-9]+ {
diff --git a/vm.c b/vm.c
index 4ffd17c..a64cb6a 100644
--- a/vm.c
+++ b/vm.c
@@ -153,8 +153,8 @@ vm_ret(int arg)
 
   pc = fun_stack[fun_top--];  
   nargs = fun_stack[fun_top--];
-  fun_top -= nargs;
-  assert(fun_top >= -1);
+  top -= nargs;
+  assert(fun_top >= -1 && top >= -1);
   scoperem(scope--);
 }
 
-- 
2.11.4.GIT