Import files provided by TATA

4 files changed, 211 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..e99acd1
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,21 @@
+TARGET = scanner
+OBJECT = lex.yy.o symboltable.o 
+CC = cc -g
+LEX = flex
+LIBS = -lfl 
+
+scanner:	lex.yy.o symboltable.o
+	$(CC) -o scanner lex.yy.o symboltable.o
+
+symboltable.o: symboltable.c 
+	$(CC) -c symboltable.c 
+
+lex.yy.o: lex.yy.c 
+	$(CC) -c lex.yy.c 
+
+lex.yy.c: lexer.l
+	$(LEX) $(LIB) lexer.l
+
+clean:
+	rm -f $(TARGET) $(OBJECT) 
+
diff --git a/header.h b/header.h
new file mode 100644
index 0000000..fd9a8aa
--- /dev/null
+++ b/header.h
@@ -0,0 +1,11 @@
+struct symtab{
+	char lexeme[256];
+	struct symtab *front;
+	struct symtab *back;
+	int line;
+	int counter;
+};
+
+typedef struct symtab symtab;
+symtab * lookup(char *name);
+void insert(char *name);
diff --git a/lexer.l b/lexer.l
new file mode 100644
index 0000000..d7be3c8
--- /dev/null
+++ b/lexer.l
@@ -0,0 +1,90 @@
+%option noyywrap 
+%{
+#include <stdio.h>
+#include "header.h" 
+int linenumber;
+symtab * lookup();
+symtab * ptr;
+void     insertID();
+void 	 printSymTab();
+/* You need to define for all tokens in C--, here are some examples */
+#define INT		10
+#define FLOAT 		11 
+#define OP_ASSIGN 	12 
+#define OP_OR 		13 
+#define MK_LPAREN 	14 
+#define MK_RPAREN 	15 
+#define ERROR 		100 
+
+%}
+
+letter   [A-Za-z]
+digit    [0-9]
+ID	 {letter}({letter}|{digit}|"_")*
+WS	 [ \t]+
+Int_constant {digit}+
+
+/* You need to define the following RE's 
+Float_constant
+String_constant
+comment
+*/
+
+OP_assign        "="
+OP_or   "||"
+
+/* Other operators appear here */ 
+
+
+newline  "\n"
+
+DL_lparen "("
+DL_rparen ")"
+DL_lbrace "{"
+DL_rbrace "}"
+DL_comma  ","
+DL_semicol ";"
+DL_dot  "."
+
+/* Other separators appear here */
+
+error    .
+
+%%
+
+{WS}            {}
+{RWInt}         {/* return INT; */ }
+{RWFloat}       {/* return FLOAT; */}
+{ID}            { 
+			ptr = lookup(yytext);
+			if (ptr == NULL)
+			     insertID(yytext);	
+			else 
+			     ptr->counter++;
+		}
+
+{OP_assign}     /* return OP_ASSIGN; */ 
+{OP_or}         /* return OP_OR; */
+{DL_lparen}     /* return MK_LPAREN; */
+{DL_rparen}     /* return MK_RPAREN; */
+{DL_lbrace}     /* return MK_LBRACE; */
+{DL_rbrace}     /* return MK_RBRACE; */
+{DL_comma}      {}
+{DL_semicol}    {}
+{newline}       linenumber += 1;
+{error}         printf("ERR \n");/* return ERROR; */
+
+
+%%
+
+main(int argc, char **argv)
+{
+ argc--; ++argv;
+   if (argc > 0)
+      yyin = fopen(argv[0], "r");
+   else
+      yyin = stdin;
+   yylex();
+   printSymTab();
+}
+
diff --git a/symboltable.c b/symboltable.c
new file mode 100644
index 0000000..0006eb2
--- /dev/null
+++ b/symboltable.c
@@ -0,0 +1,89 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<ctype.h>
+#include<math.h>
+#include"header.h"
+
+#define TABLE_SIZE	256
+
+symtab * hash_table[TABLE_SIZE];
+extern int linenumber;
+
+int HASH(char * str){
+	int idx=0;
+	while(*str){
+		idx = idx << 1;
+		idx+=*str;
+		str++;
+	}	
+	return (idx & (TABLE_SIZE-1));
+}
+
+/*returns the symbol table entry if found else NULL*/

+
+symtab * lookup(char *name){
+	int hash_key;
+	symtab* symptr;
+	if(!name)
+		return NULL;
+	hash_key=HASH(name);
+	symptr=hash_table[hash_key];
+
+	while(symptr){
+		if(!(strcmp(name,symptr->lexeme)))
+			return symptr;
+		symptr=symptr->front;
+	}
+	return NULL;
+}
+
+
+void insertID(char *name){
+	int hash_key;
+	symtab* ptr;
+	symtab* symptr=(symtab*)malloc(sizeof(symtab));	
+	
+	hash_key=HASH(name);
+	ptr=hash_table[hash_key];
+	
+	if(ptr==NULL){
+		/*first entry for this hash_key*/
+		hash_table[hash_key]=symptr;
+		symptr->front=NULL;
+		symptr->back=symptr;
+	}
+	else{
+		symptr->front=ptr;
+		ptr->back=symptr;
+		symptr->back=symptr;
+		hash_table[hash_key]=symptr;	
+	}
+	
+	strcpy(symptr->lexeme,name);
+	symptr->line=linenumber;
+	symptr->counter=1;
+}
+
+void printSym(symtab* ptr) 
+{
+	    printf(" Name = %s \n", ptr->lexeme);
+	    printf(" References = %d \n", ptr->counter);
+}
+
+void printSymTab()
+{
+    int i;
+    printf("----- Symbol Table ---------\n");
+    for (i=0; i<TABLE_SIZE; i++)
+    {
+        symtab* symptr;
+	symptr = hash_table[i];
+	while (symptr != NULL)
+	{
+            printf("====>  index = %d \n", i);
+	    printSym(symptr);
+	    symptr=symptr->front;
+	}
+    }
+}