Improved error reporting in the expression parser

Fixes 15A80F68-F233-49D9-AF0C-9908BB6903BA

4 files changed, 45 insertions, 23 deletions

diff --git a/src/parser.cc b/src/parser.cc
index e8e987cb..f52949ce 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -79,9 +79,7 @@ expr_t::parser_t::parse_value_term(std::istream&        in,
   case token_t::LPAREN:
     node = parse_value_expr(in, tflags.plus_flags(PARSE_PARTIAL)
 			    .minus_flags(PARSE_SINGLE));
-    tok = next_token(in, tflags);
-    if (tok.kind != token_t::RPAREN)
-      tok.expected(')');
+    tok = next_token(in, tflags, ')');
 
     if (node->kind == op_t::O_CONS) {
       ptr_op_t prev(node);
@@ -383,10 +381,7 @@ expr_t::parser_t::parse_querycolon_expr(std::istream& in,
 	throw_(parse_error,
 	       _("%1 operator not followed by argument") << tok.symbol);
 
-      token_t& next_tok = next_token(in, tflags.plus_flags(PARSE_OP_CONTEXT));
-      if (next_tok.kind != token_t::COLON)
-	next_tok.expected(':');
-
+      next_token(in, tflags.plus_flags(PARSE_OP_CONTEXT), ':');
       prev = node->right();
       ptr_op_t subnode = new op_t(op_t::O_COLON);
       subnode->set_left(prev);
diff --git a/src/parser.h b/src/parser.h
index 5eba4ffd..aab48830 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -52,11 +52,12 @@ class expr_t::parser_t : public noncopyable
   mutable token_t lookahead;
   mutable bool	  use_lookahead;
 
-  token_t& next_token(std::istream& in, const parse_flags_t& tflags) const {
+  token_t& next_token(std::istream& in, const parse_flags_t& tflags,
+		      const char expecting = '\0') const {
     if (use_lookahead)
       use_lookahead = false;
     else
-      lookahead.next(in, tflags);
+      lookahead.next(in, tflags, expecting);
     return lookahead;
   }
 
diff --git a/src/token.cc b/src/token.cc
index a34cdcd0..add97b8b 100644
--- a/src/token.cc
+++ b/src/token.cc
@@ -138,7 +138,8 @@ void expr_t::token_t::parse_ident(std::istream& in)
   value.set_string(buf);
 }
 
-void expr_t::token_t::next(std::istream& in, const parse_flags_t& pflags)
+void expr_t::token_t::next(std::istream& in, const parse_flags_t& pflags,
+			   const char expecting)
 {
   if (in.eof()) {
     kind = TOK_EOF;
@@ -423,6 +424,13 @@ void expr_t::token_t::next(std::istream& in, const parse_flags_t& pflags)
 	  expected('\0', c);
 
 	parse_ident(in);
+
+	if (value.as_string().length() == 0) {
+	  kind = ERROR;
+	  symbol[0] = c;
+	  symbol[1] = '\0';
+	  unexpected(expecting);
+	}
       } else {
 	kind   = VALUE;
 	value  = temp;
@@ -447,21 +455,38 @@ void expr_t::token_t::rewind(std::istream& in)
 }
 
 
-void expr_t::token_t::unexpected()
+void expr_t::token_t::unexpected(const char wanted)
 {
   kind_t prev_kind = kind;
 
   kind = ERROR;
 
-  switch (prev_kind) {
-  case TOK_EOF:
-    throw_(parse_error, _("Unexpected end of expression"));
-  case IDENT:
-    throw_(parse_error, _("Unexpected symbol '%1'") << value);
-  case VALUE:
-    throw_(parse_error, _("Unexpected value '%1'") << value);
-  default:
-    throw_(parse_error, _("Unexpected token '%1'") << symbol);
+  if (wanted == '\0') {
+    switch (prev_kind) {
+    case TOK_EOF:
+      throw_(parse_error, _("Unexpected end of expression"));
+    case IDENT:
+      throw_(parse_error, _("Unexpected symbol '%1'") << value);
+    case VALUE:
+      throw_(parse_error, _("Unexpected value '%1'") << value);
+    default:
+      throw_(parse_error, _("Unexpected expression token '%1'") << symbol);
+    }
+  } else {
+    switch (prev_kind) {
+    case TOK_EOF:
+      throw_(parse_error,
+	     _("Unexpected end of expression (wanted '%1')" << wanted));
+    case IDENT:
+      throw_(parse_error,
+	     _("Unexpected symbol '%1' (wanted '%2')") << value << wanted);
+    case VALUE:
+      throw_(parse_error,
+	     _("Unexpected value '%1' (wanted '%2')") << value << wanted);
+    default:
+      throw_(parse_error, _("Unexpected expression token '%1' (wanted '%2')")
+	     << symbol << wanted);
+    }
   }
 }
 
diff --git a/src/token.h b/src/token.h
index 8d70996b..582373cb 100644
--- a/src/token.h
+++ b/src/token.h
@@ -124,10 +124,11 @@ struct expr_t::token_t : public noncopyable
 
   int  parse_reserved_word(std::istream& in);
   void parse_ident(std::istream& in);
-  void next(std::istream& in, const parse_flags_t& flags);
+  void next(std::istream& in, const parse_flags_t& flags,
+	    const char expecting = '\0');
   void rewind(std::istream& in);
-  void unexpected();
-  void expected(char wanted, char c = '\0');
+  void unexpected(const char wanted = '\0');
+  void expected(const char wanted, char c = '\0');
 };
 
 } // namespace ledger