Revised error formatting, fixed tests

parser.go

diff --git a/parser.go b/parser.go
index d02c42b..4d3927c 100644
--- a/parser.go
+++ b/parser.go
@@ -20,6 +20,11 @@
 
 type parserStateFn func(*parser) parserStateFn
 
+// Formats and panics an error message based on a token
+func (p *parser) raiseError(tok *token, msg string, args... interface{}) {
+  panic(tok.Pos() + ": " + fmt.Sprintf(msg, args...))
+}
+
 func (p *parser) run() {
 	for state := parseStart; state != nil; {
 		state = state(p)
@@ -42,10 +47,10 @@
 func (p *parser) assume(typ tokenType) {
 	tok := p.getToken()
 	if tok == nil {
-		panic(fmt.Sprintf("%s: was expecting token %s, but token stream is empty", tok.Pos(), typ))
+		p.raiseError(tok, "was expecting token %s, but token stream is empty", tok.typ)
 	}
 	if tok.typ != typ {
-		panic(fmt.Sprintf("%s: was expecting token %s, but got %s", tok.Pos(), typ, tok.typ))
+		p.raiseError(tok, "was expecting token %s, but got %s", typ, tok.typ)
 	}
 }
 
@@ -80,7 +85,7 @@
 	case tokenEOF:
 		return nil
 	default:
-		panic(tok.Pos() + ": unexpected token")
+		p.raiseError(tok, "unexpected token")
 	}
 	return nil
 }
@@ -89,7 +94,7 @@
 	p.getToken() // discard the [[
 	key := p.getToken()
 	if key.typ != tokenKeyGroupArray {
-		panic(fmt.Sprintf("%s: unexpected token %s, was expecting a key group array", key.Pos(), key))
+		p.raiseError(key, "unexpected token %s, was expecting a key group array", key)
 	}
 
 	// get or create group array element at the indicated part in the path
@@ -101,7 +106,7 @@
 	} else if dest_tree.([]*TomlTree) != nil {
 		array = dest_tree.([]*TomlTree)
 	} else {
-		panic(fmt.Sprintf("%s: key %s is already assigned and not of type group array", key.Pos(), key))
+		p.raiseError(key, "key %s is already assigned and not of type group array", key)
 	}
 
 	// add a new tree to the end of the group array
@@ -121,11 +126,11 @@
 	p.getToken() // discard the [
 	key := p.getToken()
 	if key.typ != tokenKeyGroup {
-		panic(fmt.Sprintf("%s: unexpected token %s, was expecting a key group", key.Pos(), key))
+		p.raiseError(key, "unexpected token %s, was expecting a key group", key)
 	}
 	for _, item := range p.seenGroupKeys {
 		if item == key.val {
-			panic(key.Pos() + ": duplicated tables")
+			p.raiseError(key, "duplicated tables")
 		}
 	}
 	p.seenGroupKeys = append(p.seenGroupKeys, key.val)
@@ -154,14 +159,14 @@
 	case *TomlTree:
 		target_node = node
 	default:
-		panic(fmt.Sprintf("%s: Unknown group type for path %v", key.Pos(), group_key))
+		p.raiseError(key, "Unknown group type for path %s", group_key)
 	}
 
 	// assign value to the found group
 	local_key := []string{key.val}
 	final_key := append(group_key, key.val)
 	if target_node.GetPath(local_key) != nil {
-		panic(fmt.Sprintf("%s: the following key was defined twice: %s", key.Pos(), strings.Join(final_key, ".")))
+		p.raiseError(key, "the following key was defined twice: %s", strings.Join(final_key, "."))
 	}
 	target_node.SetPath(local_key, value)
 	return parseStart(p)
@@ -170,7 +175,7 @@
 func parseRvalue(p *parser) interface{} {
 	tok := p.getToken()
 	if tok == nil || tok.typ == tokenEOF {
-		panic(tok.Pos() + ": expecting a value")
+		p.raiseError(tok, "expecting a value")
 	}
 
 	switch tok.typ {
@@ -183,28 +188,28 @@
 	case tokenInteger:
 		val, err := strconv.ParseInt(tok.val, 10, 64)
 		if err != nil {
-			panic(err)
+			p.raiseError(tok, "%s", err)
 		}
 		return val
 	case tokenFloat:
 		val, err := strconv.ParseFloat(tok.val, 64)
 		if err != nil {
-			panic(err)
+			p.raiseError(tok, "%s", err)
 		}
 		return val
 	case tokenDate:
 		val, err := time.Parse(time.RFC3339, tok.val)
 		if err != nil {
-			panic(err)
+			p.raiseError(tok, "%s", err)
 		}
 		return val
 	case tokenLeftBracket:
 		return parseArray(p)
 	case tokenError:
-		panic(tok.val)
+		p.raiseError(tok, "%s", tok)
 	}
 
-	panic(tok.Pos() + ": never reached")
+  p.raiseError(tok, "never reached")
 
 	return nil
 }
@@ -215,7 +220,7 @@
 	for {
 		follow := p.peek()
 		if follow == nil || follow.typ == tokenEOF {
-			panic(follow.Pos() + ": unterminated array")
+			p.raiseError(follow, "unterminated array")
 		}
 		if follow.typ == tokenRightBracket {
 			p.getToken()
@@ -226,15 +231,15 @@
 			arrayType = reflect.TypeOf(val)
 		}
 		if reflect.TypeOf(val) != arrayType {
-			panic(follow.Pos() + ": mixed types in array")
+			p.raiseError(follow, "mixed types in array")
 		}
 		array = append(array, val)
 		follow = p.peek()
 		if follow == nil {
-			panic(follow.Pos() + ": unterminated array")
+			p.raiseError(follow, "unterminated array")
 		}
 		if follow.typ != tokenRightBracket && follow.typ != tokenComma {
-			panic(follow.Pos() + ": missing comma")
+			p.raiseError(follow, "missing comma")
 		}
 		if follow.typ == tokenComma {
 			p.getToken()

parser_test.go

diff --git a/parser_test.go b/parser_test.go
index 06510c0..b73fcce 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -249,12 +249,12 @@
 
 func TestFloatsWithoutLeadingZeros(t *testing.T) {
 	_, err := Load("a = .42")
-	if err.Error() != "cannot start float with a dot" {
+	if err.Error() != "(1, 4): cannot start float with a dot" {
 		t.Error("Bad error message:", err.Error())
 	}
 
 	_, err = Load("a = -.42")
-	if err.Error() != "cannot start float with a dot" {
+	if err.Error() != "(1, 5): cannot start float with a dot" {
 		t.Error("Bad error message:", err.Error())
 	}
 }