From 896e4859333c6be801391ae9bbeec425f6e32f86 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Fri, 7 May 2021 10:37:28 +0530
Subject: add prog 12: function definition

---
 12/input  |   6 ++++
 12/main.l |  44 ++++++++++++++++++++++++
 12/main.y | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 flake.nix |   1 +
 4 files changed, 163 insertions(+)
 create mode 100644 12/input
 create mode 100644 12/main.l
 create mode 100644 12/main.y

diff --git a/12/input b/12/input
new file mode 100644
index 0000000..fa64ab2
--- /dev/null
+++ b/12/input
@@ -0,0 +1,6 @@
+int main(int a, int b, int c) {
+    if (a > b) {
+        for(;;);
+        a++;
+    }
+}
diff --git a/12/main.l b/12/main.l
new file mode 100644
index 0000000..2fa1b44
--- /dev/null
+++ b/12/main.l
@@ -0,0 +1,44 @@
+%{
+extern int yylval;
+%}
+
+%%
+"void" return VOID;
+"int" return INT;
+"float" return FLOAT;
+"double" return DOUBLE;
+"char" return CHAR;
+"unsigned" return UNSIGNED;
+"long" return LONG;
+"return" return RET;
+"for" return FOR;
+"if" return IF;
+"else" return ELSE;
+"," return COMMA;
+"(" return LPAREN;
+")" return RPAREN;
+"{" return LBRACE;
+"}" return RBRACE;
+";" return ENDL;
+"++" return INC;
+"--" return DEC;
+"+" return ADD;
+"-" return SUB;
+"*" return MUL;
+"/" return DIV;
+"=" return ASSIGN;
+"==" return EQ;
+"!=" return NEQ;
+"<" return LT;
+">" return GT;
+"<=" return LTE;
+">=" return GTE;
+[a-zA-Z_][a-zA-Z_0-9]* return ID;
+. ;
+\n ;
+<<EOF>> return 0;
+%%
+
+int yywrap() {
+    return 1;
+}
diff --git a/12/main.y b/12/main.y
new file mode 100644
index 0000000..5431c55
--- /dev/null
+++ b/12/main.y
@@ -0,0 +1,112 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+int yylex();
+int yyerror(char *);
+%}
+
+%token ADD SUB MUL DIV INC DEC
+%token LT GT LTE GTE EQ NEQ ASSIGN
+%token VOID INT DOUBLE FLOAT CHAR
+%token LONG UNSIGNED
+%token COMMA LPAREN RPAREN LBRACE RBRACE
+%token ENDL
+%token FOR RET IF ELSE WHILE
+%token NUM ID
+
+%start function_definition
+
+%%
+type_modifier: LONG
+             | UNSIGNED
+             ;
+
+type_specifier: VOID
+              | CHAR
+              | INT
+              | FLOAT
+              | DOUBLE
+              | type_modifier type_specifier
+              ;
+
+argument: type_specifier ID
+        ;
+
+argument_list: argument
+             | argument COMMA argument_list
+             ;
+
+primary_expr: NUM
+            | ID
+            ;
+
+postfix_expr: postfix_expr INC
+            | postfix_expr DEC
+            | primary_expr
+            ;
+
+unary_expr: INC unary_expr
+          | DEC unary_expr
+          | postfix_expr
+          ;
+
+boolean_expr: unary_expr LT unary_expr
+            | unary_expr GT unary_expr
+            | unary_expr LTE unary_expr
+            | unary_expr GTE unary_expr
+            | unary_expr EQ unary_expr
+            | unary_expr NEQ unary_expr
+            ;
+
+assignment_expr: unary_expr ASSIGN unary_expr
+               | unary_expr ASSIGN boolean_expr
+               ;
+
+expression: unary_expr
+          | boolean_expr
+          | assignment_expr
+          ;
+
+for_expr: FOR LPAREN statement statement expression RPAREN statement
+        | FOR LPAREN statement statement RPAREN statement
+        ;
+
+while_expr: WHILE LPAREN expression RPAREN block
+          | WHILE LPAREN RPAREN block
+          ;
+
+if_expr: IF LPAREN expression RPAREN block
+       | IF LPAREN expression RPAREN block ELSE block
+       | IF LPAREN expression RPAREN block ELSE if_expr
+       ;
+
+block: LBRACE statement block_cont
+     ;
+
+block_cont: statement block_cont
+          | RBRACE
+          ;
+
+statement: RET expression ENDL
+         | expression ENDL
+         | block
+         | for_expr
+         | if_expr
+         | while_expr
+         | ENDL
+         ;
+
+function_definition: argument LPAREN argument_list RPAREN block
+                   | argument LPAREN RPAREN block
+                   ;
+%%
+
+int main() {
+    yyparse();
+    printf("valid expression");
+}
+
+int yyerror(char *s) {
+    printf("error: %s", s);
+    exit(0);
+}
diff --git a/flake.nix b/flake.nix
index 17cceb1..fb2e2cb 100644
--- a/flake.nix
+++ b/flake.nix
@@ -24,6 +24,7 @@
           { name = "09"; yacc = true; }
           { name = "10"; yacc = true; }
           { name = "11"; yacc = true; }
+          { name = "12"; yacc = true; }
         ];
         apps = builtins.listToAttrs (builtins.map
           (def:
-- 
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