use custom yylex() to directly parse command line arguments

4 files changed, 113 insertions, 93 deletions

diff --git a/Makefile b/Makefile
index 33e958f..3ebd801 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,5 @@
-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
+expr: y.tab.c y.tab.h
+	$(CC) -g -o $@ y.tab.c -ly
 
 y.tab.c y.tab.h: expr.y
 	yacc -d expr.y
diff --git a/expr.h b/expr.h
deleted file mode 100644
index 4b4a874..0000000
--- a/expr.h
+++ /dev/null
@@ -1,9 +0,0 @@
-typedef struct {
-	int type;
-	union {
-		int i;
-		char *s;
-	} u;
-} expr_yystype;
-
-#define YYSTYPE expr_yystype
diff --git a/expr.l b/expr.l
deleted file mode 100644
index 57b3de2..0000000
--- a/expr.l
+++ /dev/null
@@ -1,74 +0,0 @@
-%{
-#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]
-
-%%
-
-"|"	return '|';
-"&"	return '&';
-"="	return '=';
-">"	return '>';
-">="	return GE;
-"<"	return '<';
-"<="	return LE;
-"!="	return NE;
-"+"	return '+';
-"-"	return '-';
-"*"	return '*';
-"/"	return '/';
-"%"	return '%';
-"("	return '(';
-")"	return ')';
-":"	return ':';
-{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		;
-
-%%
-
-int main(int argc, char *argv[])
-{
-	setlocale(LC_ALL, "");
-
-	int c;
-	while ((c = getopt(argc, argv, "")) != -1) {
-		switch (c) {
-		default:
-			return -1;
-		}
-	}
-
-	if (optind >= argc) {
-		fprintf(stderr, "expr: missing operands\n");
-		return 1;
-	}
-
-	size_t n = 1;
-	for (int i = optind; i < argc; i++) {
-		n += strlen(argv[i]) + 1;
-	}
-
-	FILE *mem = fmemopen(NULL, n, "w+");
-	for (int i = optind; i < argc; i++) {
-		fprintf(mem, "%s\n", argv[i]);
-	}
-	rewind(mem);
-
-	yyin = mem;
-
-	return yyparse();
-}
diff --git a/expr.y b/expr.y
index b2f2061..f409c5c 100644
--- a/expr.y
+++ b/expr.y
@@ -1,16 +1,27 @@
 %{
+#define _XOPEN_SOURCE 700
+#include <locale.h>
+#include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+typedef struct {
+	int type;
+	union {
+		intmax_t i;
+		char *s;
+	} u;
+} expr_yystype;
+
+#define YYSTYPE expr_yystype
 
-#include "expr.h"
 #include "y.tab.h"
 
-extern int yylex(void);
+static int yylex(void);
 extern int yyerror(const char *s);
 
-static void breakpoint(void) { }
-
 static void expr_only_integers(YYSTYPE *y1, YYSTYPE *y2)
 {
 	if (y1->type == STRING) {
@@ -140,3 +151,98 @@ expr	: STRING {
 		printf("or\n");
 	}
 	;
+
+%%
+
+
+/*
+
+"|"	return '|';
+"&"	return '&';
+"="	return '=';
+">"	return '>';
+">="	return GE;
+"<"	return '<';
+"<="	return LE;
+"!="	return NE;
+"+"	return '+';
+"-"	return '-';
+"*"	return '*';
+"/"	return '/';
+"%"	return '%';
+"("	return '(';
+")"	return ')';
+":"	return ':';
+{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		;
+
+*/
+
+static char **expr_args;
+
+static int yylex(void)
+{
+	if (expr_args[optind] == NULL) {
+		return YYEOF;
+	}
+
+	char *s = expr_args[optind];
+
+	if (strlen(s) == 1) {
+		char c = s[0];
+		if (strchr("|&=+-*/%():", c)) {
+			optind++;
+			return c;
+		}
+	}
+
+	if (strlen(s) == 2) {
+		if (!strcmp(s, ">=")) {
+			optind++;
+			return GE;
+		}
+		if (!strcmp(s, "<=")) {
+			optind++;
+			return LE;
+		}
+		if (!strcmp(s, "!=")) {
+			optind++;
+			return NE;
+		}
+	}
+
+	char *end = NULL;
+	yylval.type = INTEGER;
+	yylval.u.i = strtoimax(s, &end, 10);
+	if (end && *end != '\0') {
+		yylval.type = STRING;
+		yylval.u.s = s;
+	}
+
+	optind++;
+	return yylval.type;
+}
+
+int main(int argc, char *argv[])
+{
+	setlocale(LC_ALL, "");
+
+	int c;
+	while ((c = getopt(argc, argv, "")) != -1) {
+		switch (c) {
+		default:
+			return -1;
+		}
+	}
+
+	if (optind >= argc) {
+		fprintf(stderr, "expr: missing operands\n");
+		return 1;
+	}
+
+	expr_args = argv;
+
+	return yyparse();
+}