Create basic REPL module

lib/include/repl.h

@@ -0,0 +1,35 @@
+#ifndef REPL_H
+#define REPL_H
+
+#include "memory_pool.h"
+
+#define REPL_LINE_BUFFER_SIZE 128
+#define REPL_RESULT_BUFFER_SIZE 128
+
+typedef enum {
+	REPL_OK,
+	REPL_ERROR,
+	REPL_EXIT,
+} repl_status_t;
+
+typedef int (*get_byte_fn_t)(void);
+typedef const expression_t *(*read_fn_t)(
+    memory_pool_t *pool, const char *input, int len);
+typedef int (*evaluate_fn_t)(const expression_t *expression);
+typedef void (*print_fn_t)(const char *output, int len);
+
+typedef struct {
+	get_byte_fn_t get_byte;
+	read_fn_t read;
+	evaluate_fn_t evaluate;
+	print_fn_t print;
+	memory_pool_t pool;
+	char line_buffer[REPL_LINE_BUFFER_SIZE];
+	char result_buffer[REPL_RESULT_BUFFER_SIZE];
+} repl_t;
+
+void init_repl(repl_t *repl);
+void step_repl(repl_t *repl);
+void run_repl(repl_t *repl);
+
+#endif

lib/repl.c

@@ -0,0 +1,30 @@
+#include "repl.h"
+
+#include <stdio.h>
+
+void init_repl(repl_t *repl)
+{
+	init_memory_pool(&repl->pool);
+}
+
+void step_repl(repl_t *repl)
+{
+	int len;
+	for (len = 0; len < REPL_LINE_BUFFER_SIZE; ++len) {
+		const int byte = repl->get_byte();
+		if ('\n' == byte)
+			break;
+		repl->line_buffer[len] = (char)byte;
+	}
+	const expression_t *e = repl->read(&repl->pool, repl->line_buffer, len);
+	const int result = repl->evaluate(e);
+	const int result_len = snprintf(
+	    repl->result_buffer, REPL_RESULT_BUFFER_SIZE, "%d\n", result);
+	repl->print(repl->result_buffer, result_len);
+}
+
+void run_repl(repl_t *repl)
+{
+	while (1)
+		step_repl(repl);
+}