Implement END and ctx.stop

7 files changed, 38 insertions, 15 deletions

diff --git a/README b/README
index c10b526..e131861 100644
--- a/README
+++ b/README
@@ -39,7 +39,6 @@ Originally written by Alexis Lockwood in 2021. Ⓐ
 - Non-integer variable types
   - String will always be supported
   - Floating point as optional compile-in
-- External abort mechanism
 - Better testing
 - Compile-time options for:
   - Internal asserts for better LS_INTERNAL_ERROR info
diff --git a/ls_run.c b/ls_run.c
index 7468a32..28ad4f6 100644
--- a/ls_run.c
+++ b/ls_run.c
@@ -137,9 +137,14 @@ int main(int argc, char ** argv)
 	ls_value_t pool[1000];
 	ls_error_t e = ls_run(&ls_ctx, pool, 1000);
 
-	if (e != 0)
+	if (e == LS_STOPPED)
 	{
-		fprintf(stderr, "Error %d at line %u\n",
+		fprintf(stderr, ">stopped at line %u\n",
+			ls_ctx.line);
+	}
+	else if (e != 0)
+	{
+		fprintf(stderr, ">error %d at line %u\n",
 			(int) e, ls_ctx.line);
 	}
 
diff --git a/src/ls.c b/src/ls.c
index e265ac4..1ad8f29 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -34,9 +34,13 @@ ls_error_t ls_run(ls_context_t * ctx, ls_value_t * pool, size_t szpool)
 
 	ls_init_ctx(ctx, pool, szpool);
 
-	while (ls_exec_line(ctx));
+	while (!ctx->stop)
+	{
+		if (!ls_exec_line(ctx))
+			return LS_OK;
+	}
 
-	return LS_OK;
+	return LS_STOPPED;
 }
 
 #define TO_POOL_N(p) (p ? "" : "----"), \
diff --git a/src/ls.h b/src/ls.h
index 9b1971b..2f6a4d3 100644
--- a/src/ls.h
+++ b/src/ls.h
@@ -41,6 +41,22 @@ struct ls_context_s;
 
 /// Main LS execution context struct.
 typedef struct ls_context_s {
+	/// Fetcher to retrieve data. See ls_run().
+	ls_fetcher_t fetcher;
+
+	/// Context for fetcher
+	void * fetcher_ctx;
+
+	/// Line trace hook. If not null, this will be called for each line.
+	void (*line_trace_hook)(struct ls_context_s * ctx);
+
+	/// Set true to stop execution on the next line. The interpreter will
+	/// exit with error LS_STOPPED. Note that LS_STOPPED is also given if
+	/// the interpreter encounters the END statement.
+	bool stop;
+
+	// --------- end items relevant to the user ---------
+
 	/// Execution stack.
 	ls_value_t * callstack;
 
@@ -62,14 +78,6 @@ typedef struct ls_context_s {
 	/// Current line number, 1-indexed
 	uint16_t line;
 
-	/// Fetcher to retrieve data. See ls_run().
-	ls_fetcher_t fetcher;
-	/// Context for fetcher
-	void * fetcher_ctx;
-
-	/// Line trace hook. If not null, this will be called for each line.
-	void (*line_trace_hook)(struct ls_context_s * ctx);
-
 	/// Top error-handling jmpbuf. When the interpreter encounters an error,
 	/// it should store the error code in .error and jump here.
 	jmp_buf error_jmp_buf;
diff --git a/src/ls_internal.c b/src/ls_internal.c
index 3027a14..87873f2 100644
--- a/src/ls_internal.c
+++ b/src/ls_internal.c
@@ -74,6 +74,7 @@ void ls_init_ctx(ls_context_t * ctx, ls_value_t * pool, size_t szpool)
 	ctx->labels = NULL;
 	ctx->pc = 0;
 	ctx->line = 1;
+	ctx->stop = false;
 
 	for (size_t i = 0; i < LS_LABEL_CACHE_SIZE; i++)
 		ctx->label_cache[i].pc = LS_ADDR_NULL;
diff --git a/src/ls_kw_impl.c b/src/ls_kw_impl.c
index ce22cbf..d11e932 100644
--- a/src/ls_kw_impl.c
+++ b/src/ls_kw_impl.c
@@ -43,14 +43,19 @@ void ls_kw_fun_COUNT(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_DATA(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_DEC(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_DEF(ls_context_t * ctx) { _no_impl(ctx); }
-void ls_kw_fun_END(ls_context_t * ctx) { _no_impl(ctx); }
+
+void ls_kw_fun_END(ls_context_t * ctx) { ls_throw_err(ctx, LS_STOPPED); }
+
 void ls_kw_fun_EQV(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_ERASE(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_ERROR(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_FN(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_FOR(ls_context_t * ctx) { _no_impl(ctx); }
 void ls_kw_fun_GOFUN(ls_context_t * ctx) { _no_impl(ctx); }
-void ls_kw_fun_GOSUB(ls_context_t * ctx) { _no_impl(ctx); }
+void ls_kw_fun_GOSUB(ls_context_t * ctx) {
+	ls_token_t tok;
+	ls_lex(ctx, &tok);
+	return; _no_impl(ctx); }
 void ls_kw_fun_HEX(ls_context_t * ctx) { _no_impl(ctx); }
 
 void ls_kw_fun_IF(ls_context_t * ctx) {
diff --git a/src/ls_types.h b/src/ls_types.h
index 1b3f111..8296bc2 100644
--- a/src/ls_types.h
+++ b/src/ls_types.h
@@ -276,6 +276,7 @@ typedef enum {
 	LS_PATH_NOT_FOUND,
 	LS_UNDEFINED_VARIABLE,
 	LS_BAD_KEYWORD, /// Keyword not valid here
+	LS_STOPPED,
 
 	/// To be returned by a fetcher if there is no more data. This is not
 	/// strictly an error condition; the parser should be allowed to read