Merge pull request #67 from mortie/feature/repl

Add a simple REPL

Makefile

@@ -4,7 +4,7 @@ LFLAGS = -lm
 
 .PHONY = all clean
 
-all: smoke smoke_pr bench example example2 example3
+all: smoke smoke_pr repl bench example example2 example3
 
 
 smoke: smoke.c tinyexpr.c
@@ -15,6 +15,12 @@ smoke_pr: smoke.c tinyexpr.c
 	$(CC) $(CCFLAGS) -DTE_POW_FROM_RIGHT -DTE_NAT_LOG -o $@ $^ $(LFLAGS)
 	./$@
 
+repl: repl.o tinyexpr.o
+	$(CC) $(CCFLAGS) -o $@ $^ $(LFLAGS)
+
+repl-readline: repl-readline.o tinyexpr.o
+	$(CC) $(CCFLAGS) -o $@ $^ $(LFLAGS) -lreadline
+
 bench: benchmark.o tinyexpr.o
 	$(CC) $(CCFLAGS) -o $@ $^ $(LFLAGS)
 
@@ -27,8 +33,11 @@ example2: example2.o tinyexpr.o
 example3: example3.o tinyexpr.o
 	$(CC) $(CCFLAGS) -o $@ $^ $(LFLAGS)
 
+repl-readline.o: repl.c
+	$(CC) -c -DUSE_READLINE $(CCFLAGS) $< -o $@
+
 .c.o:
 	$(CC) -c $(CCFLAGS) $< -o $@
 
 clean:
-	rm -f *.o *.exe example example2 example3 bench smoke_pr smoke
+	rm -f *.o *.exe example example2 example3 bench repl smoke_pr smoke

repl.c

@@ -0,0 +1,80 @@
+#include "tinyexpr.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifdef USE_READLINE
+#include <readline/readline.h>
+#include <readline/history.h>
+#else
+static char *readline(const char *prompt) {
+    fprintf(stderr, "%s", prompt);
+    char buf[1024];
+    char *line = fgets(buf, sizeof(buf), stdin);
+    if (line == NULL && feof(stdin)) {
+        return NULL;
+    } else if (line == NULL) {
+        perror("fgets");
+        return NULL;
+    }
+
+    size_t len = strlen(line);
+    if (line[len - 1] == '\n') {
+        line[len - 1] = '\0';
+        len -= 1;
+    }
+
+    line = malloc(len + 1);
+    strcpy(line, buf);
+    return line;
+}
+
+static void add_history(const char *line) {}
+#endif
+
+static int eval(const char *str) {
+    int err = 0;
+    double r = te_interp(str, &err);
+    if (err != 0) {
+        printf("Error at position %i\n", err);
+        return -1;
+    } else {
+        printf("%g\n", r);
+        return 0;
+    }
+}
+
+static void repl() {
+    while (1) {
+        char *line = readline("> ");
+        if (line == NULL) {
+            break;
+        } else if (strcmp(line, "q") == 0 || strcmp(line, "quit") == 0) {
+            free(line);
+            break;
+        }
+
+        if (eval(line) != -1) {
+            add_history(line);
+        }
+
+        free(line);
+    }
+}
+
+int main(int argc, char **argv) {
+    if (argc == 3 && strcmp(argv[1], "-e") == 0) {
+        if (eval(argv[2]) == -1) {
+            return 1;
+        } else {
+            return 0;
+        }
+    } else if (argc == 1) {
+        repl();
+        return 0;
+    } else {
+        printf("Usage: %s\n", argv[0]);
+        printf("       %s -e <expression>\n", argv[0]);
+        return 1;
+    }
+}