Stop tracking line numbers

9 files changed, 65 insertions, 37 deletions

diff --git a/README b/README
index 8e3fa64..ef1bda8 100644
--- a/README
+++ b/README
@@ -50,9 +50,6 @@ Originally written by Alexis Lockwood in 2021. Ⓐ
     - Fetcher (always execute in RAM)
 - Delete GOFUN, it doesn't exist anymore
 - Argument and return value support for GOSUB and RETURN
-- Stop tracking line number, it's getting too messy (esp with function calls,
-  etc). It's only needed to report errors. We can just count it out in the
-  error handler.
 
 ╒════════════════════════╕
 │ THE SCRIPTING LANGUAGE │
diff --git a/ls_run.c b/ls_run.c
index 8691ef4..307b751 100644
--- a/ls_run.c
+++ b/ls_run.c
@@ -128,7 +128,6 @@ int main(int argc, char ** argv)
 	if (action == ACT_TOKENIZE)
 	{
 		ls_ctx.pc = 0;
-		ls_ctx.line = 1;
 		ls_ctx.labels = NULL;
 		_tokenize(&ls_ctx);
 		exit(EXIT_SUCCESS);
@@ -137,15 +136,16 @@ int main(int argc, char ** argv)
 	ls_value_t pool[1000];
 	ls_error_t e = ls_run(&ls_ctx, pool, 1000);
 
+	uint16_t line = 0, col = 0;
+	ls_translate_pc(&ls_ctx, ls_ctx.pc, &line, &col);
+
 	if (e == LS_STOPPED)
 	{
-		fprintf(stderr, ">stopped at line %u\n",
-			ls_ctx.line);
+		fprintf(stderr, ">stopped at %u:%u\n", line, col);
 	}
 	else if (e != 0)
 	{
-		fprintf(stderr, ">error %d at line %u\n",
-			(int) e, ls_ctx.line);
+		fprintf(stderr, ">error %d at %u:%u\n", (int) e, line, col);
 	}
 
 	fclose(f);
@@ -159,8 +159,7 @@ int main(int argc, char ** argv)
 		{
 			ls_print_value(stdout, &pool[i], &pool[0]);
 			printf("\n");
-			//if (pool[i].ty == LS_TY_PRISTINE)
-			if (i == 10)
+			if (pool[i].ty == LS_TY_PRISTINE)
 				break;
 		}
 	}
@@ -258,8 +257,10 @@ static void _tokenize(ls_context_t * ctx)
 
 	if (setjmp(ctx->error_jmp_buf))
 	{
-		fprintf(stderr, "error %d at line %"PRIu16"\n",
-			(int) ctx->error, ctx->line);
+		uint16_t line = 0, col = 0;
+		ls_translate_pc(ctx, ctx->pc, &line, &col);
+		fprintf(stderr, "error %d at %u:%u",
+			(int) ctx->error, line, col);
 		exit(EXIT_FAILURE);
 	}
 
@@ -343,5 +344,10 @@ static void _tokenize(ls_context_t * ctx)
 
 static void _line_trace_hook(ls_context_t * ctx)
 {
-	fprintf(stderr, ">line %"PRIu16"\n", ctx->line);
+	uint16_t line = 0, col = 0;
+	bool cachedebug_hold = cachedebug;
+	cachedebug = false;
+	ls_translate_pc(ctx, ctx->pc, &line, &col);
+	cachedebug = cachedebug_hold;
+	fprintf(stderr, ">line %"PRIu16"\n", line);
 }
diff --git a/src/ls.c b/src/ls.c
index d6429e8..0f984fb 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -138,4 +138,37 @@ void ls_print_value(FILE * stream, ls_value_t * value, ls_value_t * first)
 	}
 }
 
+bool ls_translate_pc(ls_context_t * ctx, ls_addr_t pc, uint16_t * line,
+	uint16_t * col)
+{
+	uint16_t n_line = 1, n_col = 1;
+	bool last_was_nl = false;
+
+	for (ls_addr_t i = 0; i <= pc; i++)
+	{
+		int f = ctx->fetcher(ctx->fetcher_ctx, i);
+
+		if (f <= 0)
+			return false;
+
+		ls_uchar uch = (ls_uchar) f;
+
+		if (last_was_nl)
+		{
+			n_line++;
+			n_col = 1;
+		}
+		else
+		{
+			n_col++;
+		}
+
+		last_was_nl = (uch == (ls_uchar) '\n');
+	}
+
+	*line = n_line;
+	*col = n_col;
+	return true;
+}
+
 // --- PRIVATE FUNCTION DEFINITIONS --------------------------------------------
diff --git a/src/ls.h b/src/ls.h
index 2f6a4d3..75ff0f2 100644
--- a/src/ls.h
+++ b/src/ls.h
@@ -75,9 +75,6 @@ typedef struct ls_context_s {
 	/// Program counter
 	ls_addr_t pc;
 
-	/// Current line number, 1-indexed
-	uint16_t line;
-
 	/// 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;
@@ -105,6 +102,21 @@ typedef struct ls_context_s {
 /// @param szpool - number of elements in @a pool
 ls_error_t ls_run(ls_context_t * ctx, ls_value_t * pool, size_t szpool);
 
+/// Convert a program counter value to a line and column number. This is
+/// expensive and should only be called in rare cases (for example, printing
+/// out a line number in an error message).
+///
+/// @param ctx - context
+/// @param pc - program counter to look up
+/// @param[out] line - 1-based line number
+/// @param[out] col - 1-based column number
+/// @retval true - success
+/// @retval false - the PC doesn't exist
+///
+/// If the PC doesn't exist, @a line and @a col are unchanged.
+bool ls_translate_pc(ls_context_t * ctx, ls_addr_t pc, uint16_t * line,
+	uint16_t * col);
+
 /// Print out a ls_value_t. For diagnostics.
 ///
 /// @param stream - stream to print it into
diff --git a/src/ls_expr.c b/src/ls_expr.c
index 20eb787..f6bfd2a 100644
--- a/src/ls_expr.c
+++ b/src/ls_expr.c
@@ -157,7 +157,6 @@ void ls_eval_expr(ls_context_t * ctx, ls_value_t * val, ls_token_t * firsttok)
 	while (!done)
 	{
 		ls_addr_t pc_save = ctx->pc;
-		uint16_t line_save = ctx->line;
 
 		ls_lex(ctx, &tok);
 have_token:
@@ -190,7 +189,6 @@ have_token:
 		if (done) {
 			// Don't eat the token that ended the line
 			ctx->pc = pc_save;
-			ctx->line = line_save;
 		}
 	}
 
diff --git a/src/ls_goto.c b/src/ls_goto.c
index ef0c9eb..1c198c3 100644
--- a/src/ls_goto.c
+++ b/src/ls_goto.c
@@ -30,7 +30,6 @@ static bool _rewind_line(ls_context_t * ctx);
 void ls_goto_num(ls_context_t * ctx, bool backward, uint16_t num)
 {
 	ls_addr_t target = LS_ADDR_NULL;
-	uint16_t tline;
 
 	for (size_t i = 0; i < LS_LABEL_CACHE_SIZE; i++)
 	{
@@ -42,16 +41,14 @@ void ls_goto_num(ls_context_t * ctx, bool backward, uint16_t num)
 				(ctx->label_cache[i].pc <= ctx->pc && backward))
 			{
 				target = ctx->label_cache[i].pc;
-				tline = ctx->label_cache[i].line;
 				break;
 			}
 		}
 	}
 
-	// In case we can't find the label, save pc/line to "unwind" for a
+	// In case we can't find the label, save pc to "unwind" for a
 	// more helpful error later
 	ls_addr_t pc = ctx->pc;
-	uint16_t line = ctx->line;
 
 	if (target == LS_ADDR_NULL && !backward)
 	{
@@ -66,7 +63,6 @@ void ls_goto_num(ls_context_t * ctx, bool backward, uint16_t num)
 				if (tok.body.number_val == num)
 				{
 					target = ctx->pc;
-					tline = ctx->line;
 					break;
 				}
 			}
@@ -87,20 +83,17 @@ void ls_goto_num(ls_context_t * ctx, bool backward, uint16_t num)
 			// Quickly saving and restoring our location avoids
 			// a costly second rewind to undo the ls_lex().
 			ls_addr_t bw_pc = ctx->pc++;
-			uint16_t bw_line = ctx->line++;
 			ls_lex(ctx, &tok);
 			if (tok.ty == LS_TOK_NUM_LABEL)
 			{
 				if (tok.body.number_val == num)
 				{
 					target = ctx->pc;
-					tline = ctx->line;
 					break;
 				}
 			}
 
 			ctx->pc = bw_pc;
-			ctx->line = bw_line;
 		}
 	}
 
@@ -108,13 +101,11 @@ void ls_goto_num(ls_context_t * ctx, bool backward, uint16_t num)
 	{
 throw:
 		ctx->pc = pc;
-		ctx->line = line;
 		ls_throw_err(ctx, LS_UNDEFINED_LABEL);
 	}
 	else
 	{
 		ctx->pc = target;
-		ctx->line = tline;
 	}
 }
 
@@ -161,7 +152,6 @@ void ls_goto_ident(ls_context_t * ctx, char const * ident)
 		ls_throw_err(ctx, LS_UNDEFINED_LABEL);
 
 	ctx->pc = label->body.label.pc;
-	ctx->line = (uint16_t) (uintptr_t) label->prev;
 }
 
 // --- PRIVATE FUNCTION DEFINITIONS --------------------------------------------
@@ -180,7 +170,6 @@ static bool _rewind_line(ls_context_t * ctx)
 		if (ch == '\n')
 		{
 			ctx->pc = pc;
-			--ctx->line;
 			return true;
 		}
 
diff --git a/src/ls_internal.c b/src/ls_internal.c
index 87873f2..8d63fa3 100644
--- a/src/ls_internal.c
+++ b/src/ls_internal.c
@@ -73,7 +73,6 @@ void ls_init_ctx(ls_context_t * ctx, ls_value_t * pool, size_t szpool)
 	ctx->funcs = NULL;
 	ctx->labels = NULL;
 	ctx->pc = 0;
-	ctx->line = 1;
 	ctx->stop = false;
 
 	for (size_t i = 0; i < LS_LABEL_CACHE_SIZE; i++)
diff --git a/src/ls_lex.c b/src/ls_lex.c
index f8ff0d0..186e789 100644
--- a/src/ls_lex.c
+++ b/src/ls_lex.c
@@ -103,8 +103,6 @@ void ls_lex(ls_context_t * ctx, ls_token_t * tok)
 		break;
 
 	case CH_KIND_LINESEP:
-		ctx->line++;
-		// fall through
 	case CH_KIND_SEP:
 		tok->ty = LS_TOK_STATEMENT_SEP;
 		break;
@@ -312,7 +310,6 @@ static void _lex_num(ls_context_t * ctx, ls_token_t * tok, ls_uchar ch[2])
 			ls_label_cache_t * lc
 				= &ctx->label_cache[ctx->label_cache_i];
 			lc->pc = (ls_addr_t)(ctx->pc + 1);
-			lc->line = ctx->line;
 			lc->num = (ls_addr_t)(tok->body.number_val);
 			tok->ty = LS_TOK_NUM_LABEL;
 		}
@@ -399,7 +396,6 @@ static void _lex_word(ls_context_t * ctx, ls_token_t * tok, ls_uchar ch[2])
 			strncpy(label->body.label.ident, tok->body.word_val,
 				LS_IDENT_LEN);
 			label->body.label.pc = ctx->pc;
-			label->prev = (void *) (uintptr_t) ctx->line;
 			ctx->labels = label;
 		}
 	}
diff --git a/src/ls_types.h b/src/ls_types.h
index 567b926..9df404e 100644
--- a/src/ls_types.h
+++ b/src/ls_types.h
@@ -205,7 +205,6 @@ typedef struct ls_value_s {
 	/// Internal types:
 	///   - Stack frames: PREV points at the stack frame above this one.
 	///     NEXT points at the variable scope.
-	///   - Labels: PREV contains a line number cast to a pointer (sorry)
 	///   - Others: as defined in those types' documentation.
 	struct ls_value_s * prev, * next;
 	union {
@@ -231,7 +230,6 @@ typedef struct ls_value_s {
 /// needing to scan the code.
 typedef struct {
 	ls_addr_t pc;
-	uint16_t line;
 	uint16_t num;
 } ls_label_cache_t;