88 lines
1.6 KiB
Go
88 lines
1.6 KiB
Go
// Copyright 2016 The Xorm Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package builder
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import (
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"bytes"
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"io"
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)
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// Writer defines the interface
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type Writer interface {
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io.Writer
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Append(...interface{})
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}
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var _ Writer = NewWriter()
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// BytesWriter implments Writer and save SQL in bytes.Buffer
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type BytesWriter struct {
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writer *bytes.Buffer
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buffer []byte
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args []interface{}
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}
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// NewWriter creates a new string writer
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func NewWriter() *BytesWriter {
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w := &BytesWriter{}
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w.writer = bytes.NewBuffer(w.buffer)
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return w
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}
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// Write writes data to Writer
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func (s *BytesWriter) Write(buf []byte) (int, error) {
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return s.writer.Write(buf)
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}
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// Append appends args to Writer
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func (s *BytesWriter) Append(args ...interface{}) {
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s.args = append(s.args, args...)
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}
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// Cond defines an interface
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type Cond interface {
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WriteTo(Writer) error
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And(...Cond) Cond
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Or(...Cond) Cond
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IsValid() bool
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}
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type condEmpty struct{}
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var _ Cond = condEmpty{}
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// NewCond creates an empty condition
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func NewCond() Cond {
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return condEmpty{}
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}
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func (condEmpty) WriteTo(w Writer) error {
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return nil
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}
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func (condEmpty) And(conds ...Cond) Cond {
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return And(conds...)
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}
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func (condEmpty) Or(conds ...Cond) Cond {
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return Or(conds...)
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}
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func (condEmpty) IsValid() bool {
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return false
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}
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func condToSQL(cond Cond) (string, []interface{}, error) {
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if cond == nil || !cond.IsValid() {
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return "", nil, nil
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}
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w := NewWriter()
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if err := cond.WriteTo(w); err != nil {
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return "", nil, err
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}
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return w.writer.String(), w.args, nil
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}
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