From 9285974bffe15033acc4413c5dd275cd8722466f Mon Sep 17 00:00:00 2001
From: Přemysl Janouch <p.janouch@gmail.com>
Date: Fri, 1 May 2015 18:39:38 +0200
Subject: Fix error reporting in configuration parsing

---
 common.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 64 insertions(+), 15 deletions(-)

diff --git a/common.c b/common.c
index 5f86396..4b7e6bf 100644
--- a/common.c
+++ b/common.c
@@ -673,16 +673,42 @@ enum config_token
 	CONFIG_T_STRING                     ///< CONFIG_ITEM_STRING{,_LIST}
 };
 
+static const char *
+config_token_name (enum config_token token)
+{
+	switch (token)
+	{
+	case CONFIG_T_ABORT:    return "end of input";
+
+	case CONFIG_T_WORD:     return "word";
+	case CONFIG_T_EQUALS:   return "equal sign";
+	case CONFIG_T_LBRACE:   return "left brace";
+	case CONFIG_T_RBRACE:   return "right brace";
+	case CONFIG_T_NEWLINE:  return "newline";
+
+	case CONFIG_T_NULL:     return "null value";
+	case CONFIG_T_BOOLEAN:  return "boolean";
+	case CONFIG_T_INTEGER:  return "integer";
+	case CONFIG_T_STRING:   return "string";
+
+	default:
+		hard_assert (!"invalid token value");
+	}
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
 struct config_tokenizer
 {
-	const char *p;
-	size_t len;
+	const char *p;                      ///< Current position in input
+	size_t len;                         ///< How many bytes of input are left
 
-	unsigned line;
-	unsigned column;
+	bool report_line;                   ///< Whether to count lines at all
+	unsigned line;                      ///< Current line
+	unsigned column;                    ///< Current column
 
-	int64_t integer;
-	struct str string;
+	int64_t integer;                    ///< Parsed boolean or integer value
+	struct str string;                  ///< Parsed string value
 };
 
 /// Input has to be null-terminated anyway
@@ -692,6 +718,7 @@ config_tokenizer_init (struct config_tokenizer *self, const char *p, size_t len)
 	memset (self, 0, sizeof *self);
 	self->p = p;
 	self->len = len;
+	self->report_line = true;
 	str_init (&self->string);
 }
 
@@ -711,7 +738,7 @@ static int
 config_tokenizer_advance (struct config_tokenizer *self)
 {
 	int c = *self->p++;
-	if (c == '\n')
+	if (c == '\n' && self->report_line)
 	{
 		self->column = 0;
 		self->line++;
@@ -723,13 +750,29 @@ config_tokenizer_advance (struct config_tokenizer *self)
 	return c;
 }
 
+static void config_tokenizer_error (struct config_tokenizer *self,
+	struct error **e, const char *format, ...) ATTRIBUTE_PRINTF (3, 4);
+
 static void
 config_tokenizer_error (struct config_tokenizer *self,
-	struct error **e, const char *description)
+	struct error **e, const char *format, ...)
 {
-	// FIXME: we don't always want to specify the line
-	error_set (e, "near line %u, column %u: %s",
-		self->line + 1, self->column + 1, description);
+	struct str description;
+	str_init (&description);
+
+	va_list ap;
+	va_start (ap, format);
+	str_append_vprintf (&description, format, ap);
+	va_end (ap);
+
+	if (self->report_line)
+		error_set (e, "near line %u, column %u: %s",
+			self->line + 1, self->column + 1, description.str);
+	else
+		error_set (e, "near character %u: %s",
+			self->column + 1, description.str);
+
+	str_free (&description);
 }
 
 static enum config_token
@@ -856,9 +899,10 @@ config_parser_expect
 	if (config_parser_accept (self, token, out))
 		return;
 
-	// TODO: fill in "X" and "Y"
 	config_tokenizer_error (&self->tokenizer, &self->error,
-		"unexpected X, expected Y");
+		"unexpected `%s', expected `%s'",
+		config_token_name (self->token),
+		config_token_name (token));
 	longjmp (out, 1);
 }
 
@@ -903,9 +947,9 @@ config_parser_parse_value (struct config_parser *self, jmp_buf out)
 	if (ACCEPT (CONFIG_T_STRING))
 		return config_item_string (&self->tokenizer.string);
 
-	// TODO: fill in "X" as the token name
 	config_tokenizer_error (&self->tokenizer, &self->error,
-		"unexpected X, expected a value");
+		"unexpected `%s', expected a value",
+		config_token_name (self->token));
 	longjmp (out, 1);
 }
 
@@ -1003,7 +1047,12 @@ config_item_parse (const char *script, size_t len,
 	}
 
 	if (single_value_only)
+	{
+		// This is really only intended for in-program configuration
+		// and telling the line number would look awkward
+		parser.tokenizer.report_line = false;
 		object = config_parser_parse_value (&parser, err);
+	}
 	else
 		object = config_parser_parse_object (&parser, err);
 	config_parser_expect (&parser, CONFIG_T_ABORT, err);
-- 
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