Rewrite Engine.QuoteTo() to accept multi-part identifiers (#1476)

Author: Guillermo Prandi

engine.go

@@ -207,25 +207,46 @@ func (engine *Engine) QuoteTo(buf *strings.Builder, value string) {
 		return
 	}
 
-	quotePair := engine.dialect.Quote("")
+	quoteTo(buf, engine.dialect.Quote(""), value)
+}
 
-	if value[0] == '`' || len(quotePair) < 2 || value[0] == quotePair[0] { // no quote
+func quoteTo(buf *strings.Builder, quotePair string, value string) {
+	if len(quotePair) < 2 { // no quote
 		_, _ = buf.WriteString(value)
 		return
-	} else {
-		prefix, suffix := quotePair[0], quotePair[1]
-
-		_ = buf.WriteByte(prefix)
-		for i := 0; i < len(value); i++ {
-			if value[i] == '.' {
-				_ = buf.WriteByte(suffix)
-				_ = buf.WriteByte('.')
-				_ = buf.WriteByte(prefix)
+	}
+	
+	prefix, suffix := quotePair[0], quotePair[1]
+
+	i := 0
+	for i < len(value) {
+		// start of a token; might be already quoted
+		if value[i] == '.' {
+			_ = buf.WriteByte('.')
+			i++
+		} else if value[i] == prefix || value[i] == '`' {
+			// Has quotes; skip/normalize `name` to prefix+name+sufix
+			var ch byte
+			if value[i] == prefix {
+				ch = suffix
 			} else {
+				ch = '`'
+			}
+			i++
+			_ = buf.WriteByte(prefix)
+			for ; i < len(value) && value[i] != ch; i++ {
+				_ = buf.WriteByte(value[i])
+			}
+			_ = buf.WriteByte(suffix)
+			i++
+		} else {
+			// Requires quotes
+			_ = buf.WriteByte(prefix)
+			for ; i < len(value) && value[i] != '.'; i++ {
 				_ = buf.WriteByte(value[i])
 			}
+			_ = buf.WriteByte(suffix)
 		}
-		_ = buf.WriteByte(suffix)
 	}
 }
 

engine_test.go

@@ -0,0 +1,41 @@
+// Copyright 2019 The Xorm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xorm
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestQuoteTo(t *testing.T) {
+
+	test := func(t *testing.T, expected string, value string) {
+		buf := &strings.Builder{}
+		quoteTo(buf, "[]", value)
+		assert.EqualValues(t, expected, buf.String())
+	}
+
+	test(t, "[mytable]", "mytable")
+	test(t, "[mytable]", "`mytable`")
+	test(t, "[mytable]", `[mytable]`)
+
+	test(t, `["mytable"]`, `"mytable"`)
+
+	test(t, "[myschema].[mytable]", "myschema.mytable")
+	test(t, "[myschema].[mytable]", "`myschema`.mytable")
+	test(t, "[myschema].[mytable]", "myschema.`mytable`")
+	test(t, "[myschema].[mytable]", "`myschema`.`mytable`")
+	test(t, "[myschema].[mytable]", `[myschema].mytable`)
+	test(t, "[myschema].[mytable]", `myschema.[mytable]`)
+	test(t, "[myschema].[mytable]", `[myschema].[mytable]`)
+
+	test(t, `["myschema].[mytable"]`, `"myschema.mytable"`)
+
+	buf := &strings.Builder{}
+	quoteTo(buf, "", "noquote")
+	assert.EqualValues(t, "noquote", buf.String())
+}