1 files changed, 150 insertions, 3 deletions

diff --git a/src/lib/syntax.c b/src/lib/syntax.c
index c1a5a85..504bb74 100644
--- a/src/lib/syntax.c
+++ b/src/lib/syntax.c
@@ -1,9 +1,156 @@
 #include "aplwc_internal.h"
 
+struct scan_state {
+	struct string *text;
+	size_t offset;
+};
+
+static void
+init_scan_state(struct scan_state *state, struct string *text)
+{
+	state->text = text;
+	state->offset = 0;
+}
+
+static int
+is_space(uint32_t c)
+{
+	return c == ' ';
+}
+
+static int
+is_letter(uint32_t c)
+{
+	return ((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z'));
+}
+
+static int
+is_digit(uint32_t c)
+{
+	return (c >= '0') && (c <= '9');
+}
+
+static uint32_t
+peek(struct scan_state *state)
+{
+	return string_char(state->text, state->offset);
+}
+
+static void
+advance(struct scan_state *state)
+{
+	state->offset += char_length(state->text, state->offset);
+}
+
+static void
+skip_space(struct scan_state *state)
+{
+	while(is_space(peek(state)))
+		advance(state);
+}
+
+static void
+identifier(struct scan_state *state, struct token *token)
+{
+	uint32_t c;
+	assert(is_letter(peek(state)));
+
+	do{
+		advance(state);
+		c = peek(state);
+	}while(is_letter(c) || is_digit(c) || (c == '_'));
+
+	token->tag = TOKEN_TAG_IDENTIFIER;
+}
+
+static enum aplwc_rc
+next_token(struct scan_state *state, struct token *token)
+{
+	uint32_t c;
+
+	skip_space(state);
+
+	c = peek(state);
+	if(is_letter(c)){
+		identifier(state, token);
+		return APLWC_OK;
+	}
+	if(c == '\n'){
+		advance(state);
+		token->tag = TOKEN_TAG_NEWLINE;
+		return APLWC_OK;
+	}
+
+	return APLWC_INVALID_SYNTAX;
+}
+
+static enum aplwc_rc 
+check(struct string *text, size_t *n)
+{
+	struct scan_state state;
+	struct token token;
+	enum aplwc_rc ret;
+	size_t count;
+
+	init_scan_state(&state, text);
+
+	for(count = 0; peek(&state); count++){
+		ret = next_token(&state, &token);
+		if(ret != APLWC_OK)
+			return ret;
+	}
+
+	*n = count;
+	return APLWC_OK;
+}
+
+static void
+scan(struct string *text, struct token_list *tokens)
+{
+	struct scan_state state;
+	enum aplwc_rc ret;
+	size_t count;
+
+	init_scan_state(&state, text);
+
+	for(count = 0; peek(&state); count++){
+		ret = next_token(&state, &tokens->tokens[count]);
+		assert(ret == APLWC_OK);
+	}
+}
+
 struct token_list *
 scan_line(struct aplwc *aplwc, struct string *text)
 {
-	aplwc->last_error = APLWC_NOT_YET_IMPLEMENTED;
-	UNUSED_PARAMETER(text);
-	return NULL;
+	enum aplwc_rc rc;
+	struct token_list *tokens;
+	size_t n, i;
+
+	rc = check(text, &n);
+	if(rc != APLWC_OK){
+		aplwc->last_error = rc;
+		return NULL;
+	}
+
+	tokens = memory_alloc_token_list(&aplwc->memory, n);
+	if(tokens == NULL){
+		aplwc->last_error = APLWC_OUT_OF_MEMORY;
+		return NULL;
+	}
+	tokens->length = n;
+	scan(text, tokens);
+
+	for(i = 0; i < n; i++){
+		if(tokens->tokens[i].tag != TOKEN_TAG_NEWLINE)
+			continue;
+
+		for(i++; i < n; i++){
+			if(tokens->tokens[i].tag != TOKEN_TAG_NEWLINE){
+				memory_free_token_list(&aplwc->memory, tokens);
+				return NULL;
+			}
+		}
+	}
+
+	return tokens;
 }