From 028f700584306cd465ddb18231ecc41c17418082 Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Sun, 17 Apr 2022 14:26:10 -0400
Subject: initial commit recognizing tokens

---
 Makefile |  7 +++++++
 expr.h   |  0
 expr.l   | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 Makefile
 create mode 100644 expr.h
 create mode 100644 expr.l

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5fda526
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,7 @@
+expr: expr.c
+	$(CC) -g -o $@ expr.c -ll
+
+expr.c: expr.l
+	lex  -t expr.l > expr.c
+
+
diff --git a/expr.h b/expr.h
new file mode 100644
index 0000000..e69de29
diff --git a/expr.l b/expr.l
new file mode 100644
index 0000000..7612ebf
--- /dev/null
+++ b/expr.l
@@ -0,0 +1,68 @@
+%{
+#define _XOPEN_SOURCE 2
+#include <locale.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "expr.h"
+%}
+
+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);
+
+%%
+
+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]);
+	}
+	fprintf(mem, "\n");
+	rewind(mem);
+
+	yyin = mem;
+
+
+	return yylex();
+}
-- 
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