Added basic code for DAG and python modifications

Author: PalAditya

Lab12-AST/3address(old).l

@@ -0,0 +1,18 @@
+%{
+#include "3address(old).tab.h"
+extern char yyval;
+%}
+
+%%
+
+[0-9]+ {yylval.symbol=(char)(yytext[0]);return NUMBER;}
+[a-z] {yylval.symbol= (char)(yytext[0]);return LETTER;}
+. {return yytext[0];}
+\n {return 0;}
+
+%%
+
+int yywrap()
+{
+ return 1;
+}

Lab12-AST/3address(old).y

@@ -0,0 +1,80 @@
+%{
+#include<stdio.h>
+char addtotable(char,char,char);
+void yyerror(char *s);
+int index1=0;
+char temp = 'A'-1;
+struct expr{
+char operand1;
+char operand2;
+char operator;
+char result;
+};
+%}
+
+%union{
+char symbol;
+}
+
+%left '+' '-'
+%left '/' '*'
+
+%token <symbol> LETTER NUMBER
+%type <symbol> exp
+%%
+
+statement: LETTER '=' exp ';' {addtotable((char)$1,(char)$3,'=');};
+exp: exp '+' exp {$$ = addtotable((char)$1,(char)$3,'+');}
+    |exp '-' exp {$$ = addtotable((char)$1,(char)$3,'-');}
+    |exp '/' exp {$$ = addtotable((char)$1,(char)$3,'/');}
+    |exp '*' exp {$$ = addtotable((char)$1,(char)$3,'*');}
+    |'(' exp ')' {$$= (char)$2;}
+    |NUMBER {$$ = (char)$1;}
+    |LETTER {(char)$1;};
+
+%%
+
+struct expr arr[20]; 
+
+void yyerror(char *s){
+    //printf("Error %s",s);
+}
+
+char addtotable(char a, char b, char o){
+    temp++;
+    arr[index1].operand1 =a;
+    arr[index1].operand2 = b;
+    arr[index1].operator = o;
+    arr[index1].result=temp;
+    index1++;
+    return temp;
+}
+
+void threeAddressCode(){
+    int i=0;
+    char temp='A';
+    while(i<index1){
+        printf("%c := ",arr[i].result);
+        printf("%c ",arr[i].operand1);
+        printf("%c ",arr[i].operator);
+        printf("%c ",arr[i].operand2);
+        i++;
+        temp++;
+        printf("\n");
+    }
+}
+
+int find(char l){
+    int i;
+    for(i=0;i<index1;i++)
+        if(arr[i].result==l) break;
+    return i;
+}
+
+
+int main(){
+    printf("Enter the expression: ");
+    yyparse();
+    threeAddressCode();
+    return 0;
+}

Lab12-AST/3address.l

@@ -1,12 +1,36 @@
 %{
-#include "3address.tab.h"
-extern char yyval;
+#include <stdio.h>
+#include <string.h>
+char symtab[100][100];
+char* pop();
+void push(char *s);
+int top=-1;
 %}
-
 %%
 
-[0-9]+ {yylval.symbol=(char)(yytext[0]);return NUMBER;}
-[a-z] {yylval.symbol= (char)(yytext[0]);return LETTER;}
+[0-9]+ {
+		node *newnode=(node *)malloc(sizeof(node));
+		strcpy(newnode->addr,yytext);
+		int i;
+		for(i=0;i<100;i++)
+			newnode->code[i]='\0';
+		//printf("Address and code are: %s,%s\n",newnode->addr,newnode->code);
+		yylval=newnode;
+		push(yytext);
+		return NUMBER;
+		}
+[a-z]+ {
+		node *newnode=(node *)malloc(sizeof(node));
+		strcpy(newnode->addr,yytext);
+		int i;
+		for(i=0;i<100;i++)
+			newnode->code[i]='\0';
+		//printf("Address and code are: %s,%s\n",newnode->addr,newnode->code);
+		yylval=newnode;
+		push(yytext);
+		return ID;
+		}
+
 . {return yytext[0];}
 \n {return 0;}
 
@@ -15,4 +39,29 @@ extern char yyval;
 int yywrap()
 {
  return 1;
+}
+/*
+//---RELOP---
+[<>]|<=|>= {
+		node *newnode=(node *)malloc(sizeof(node));
+		strcpy(newnode->addr,yytext);
+		int i;
+		for(i=0;i<100;i++)
+			newnode->code[i]='\0';
+		//printf("Address and code are: %s,%s\n",newnode->addr,newnode->code);
+		yylval=newnode;
+		push(yytext);
+		return RELOP;
+		}
+*/
+
+void push(char *s)
+{
+	//printf("Pushed %s\n",s);
+	strcpy(symtab[++top],s);
+}
+char *pop()
+{
+	//printf("Popped %s\n",symtab[top]);
+	return symtab[top--];
 }