4 files changed, 105 insertions, 25 deletions

diff --git a/Makefile b/Makefile
index 5fda526..33e958f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
-expr: expr.c
-	$(CC) -g -o $@ expr.c -ll
+expr: expr.c y.tab.c y.tab.h
+	$(CC) -g -o $@ expr.c y.tab.c -ll -ly
 
 expr.c: expr.l
 	lex  -t expr.l > expr.c
 
-
+y.tab.c y.tab.h: expr.y
+	yacc -d expr.y
diff --git a/expr.h b/expr.h
index e69de29..4b4a874 100644
--- a/expr.h
+++ b/expr.h
@@ -0,0 +1,9 @@
+typedef struct {
+	int type;
+	union {
+		int i;
+		char *s;
+	} u;
+} expr_yystype;
+
+#define YYSTYPE expr_yystype
diff --git a/expr.l b/expr.l
index 7612ebf..d6aa239 100644
--- a/expr.l
+++ b/expr.l
@@ -1,34 +1,42 @@
 %{
-#define _XOPEN_SOURCE 2
+#define _XOPEN_SOURCE 700
 #include <locale.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>
+
 #include "expr.h"
+
+#include "y.tab.h"
+
+extern int yyparse(void);
+
 %}
 
 DIGIT [0-9]
 
 %%
 
-"|"	puts("or");
-"&"	puts("and");
-"="	puts("equal");
-">"	puts("greater");
-">="	puts("greater or equal");
-"<"	puts("less");
-"<="	puts("less or equal");
-"!="	puts("not equal");
-"+"	puts("plus");
-"-"	puts("minus");
-"*"	puts("times");
-"/"	puts("divide");
-"%"	puts("remainder");
-"("	puts("lparen");
-")"	puts("rparen");
-{DIGIT}+	printf("number %s\n", yytext);
--{DIGIT}+	printf("negative %s\n", yytext);
-.+		printf("string '%s'\n", yytext);
+"|"	return OR;
+"&"	return AND;
+"="	return COMPARISON;
+">"	return COMPARISON;
+">="	return COMPARISON;
+"<"	return COMPARISON;
+"<="	return COMPARISON;
+"!="	return COMPARISON;
+"+"	return '+';
+"-"	return '-';;
+"*"	return MULTIPLICATION;
+"/"	return MULTIPLICATION;
+"%"	return MULTIPLICATION;
+"("	return '(';
+")"	return ')';
+":"	return MATCH;
+{DIGIT}+	{ yylval.u.i = atoi(yytext); return yylval.type = INTEGER; }
+-{DIGIT}+	{ yylval.u.i = atoi(yytext); return yylval.type = INTEGER; }
+.+		{ yylval.u.s = strdup(yytext); return yylval.type = STRING; }
+\n		;
 
 %%
 
@@ -58,11 +66,9 @@ int main(int argc, char *argv[])
 	for (int i = optind; i < argc; i++) {
 		fprintf(mem, "%s\n", argv[i]);
 	}
-	fprintf(mem, "\n");
 	rewind(mem);
 
 	yyin = mem;
 
-
-	return yylex();
+	return yyparse();
 }
diff --git a/expr.y b/expr.y
new file mode 100644
index 0000000..950a772
--- /dev/null
+++ b/expr.y
@@ -0,0 +1,64 @@
+%{
+#include <stdio.h>
+
+#include "expr.h"
+
+extern int yylex(void);
+extern int yyerror(const char *s);
+
+static void breakpoint(void) { }
+%}
+
+%token INTEGER
+%token STRING
+%token '(' ')'
+%left MATCH MULTIPLICATION 
+%left '+' '-'
+%left COMPARISON AND OR
+
+%start expr
+
+%%
+
+expr	: STRING {
+		printf("string\n");
+	}
+
+	| INTEGER {
+		printf("integer %d\n", $1.u.i);
+	}
+	
+	| '(' expr ')' {
+		printf("a parenthesized expression\n");
+	}
+
+	| expr MATCH expr {
+		printf("match two\n");
+	}
+
+	| expr MULTIPLICATION expr {
+		printf("multiplicationish\n");
+	}
+
+	| expr '+' expr {
+		printf("plus\n");
+		$$.u.i = $1.u.i + $3.u.i;
+		printf("%d\n", $$.u.i);
+	}
+
+	| expr '-' expr {
+		printf("minus\n");
+	}
+
+	| expr COMPARISON expr {
+		printf("compare\n");
+	}
+
+	| expr AND expr {
+		printf("and\n");
+	}
+
+	| expr OR expr {
+		printf("or\n");
+	}
+	;