dnscrypt-proxy/vendor/github.com/denis-tingajkin/go-header/value.go

129 lines
2.9 KiB
Go

// Copyright (c) 2020 Denis Tingajkin
//
// SPDX-License-Identifier: Apache-2.0
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package goheader
import (
"errors"
"fmt"
"regexp"
"strings"
)
type Calculable interface {
Calculate(map[string]Value) error
Get() string
}
type Value interface {
Calculable
Read(*Reader) Issue
}
func calculateValue(calculable Calculable, values map[string]Value) (string, error) {
sb := strings.Builder{}
r := calculable.Get()
var endIndex int
var startIndex int
for startIndex = strings.Index(r, "{{"); startIndex >= 0; startIndex = strings.Index(r, "{{") {
_, _ = sb.WriteString(r[:startIndex])
endIndex = strings.Index(r, "}}")
if endIndex < 0 {
return "", errors.New("missed value ending")
}
subVal := strings.ToLower(strings.TrimSpace(r[startIndex+2 : endIndex]))
if val := values[subVal]; val != nil {
if err := val.Calculate(values); err != nil {
return "", err
}
sb.WriteString(val.Get())
} else {
return "", fmt.Errorf("unknown value name %v", subVal)
}
endIndex += 2
r = r[endIndex:]
}
_, _ = sb.WriteString(r)
return sb.String(), nil
}
type ConstValue struct {
RawValue string
}
func (c *ConstValue) Calculate(values map[string]Value) error {
v, err := calculateValue(c, values)
if err != nil {
return err
}
c.RawValue = v
return nil
}
func (c *ConstValue) Get() string {
return c.RawValue
}
func (c *ConstValue) Read(s *Reader) Issue {
l := s.Location()
p := s.Position()
for _, ch := range c.Get() {
if ch != s.Peek() {
s.SetPosition(p)
f := s.ReadWhile(func(r rune) bool {
return r != '\n'
})
return NewIssueWithLocation(fmt.Sprintf("Expected:%v, Actual: %v", c.Get(), f), l)
}
s.Next()
}
return nil
}
type RegexpValue struct {
RawValue string
}
func (r *RegexpValue) Calculate(values map[string]Value) error {
v, err := calculateValue(r, values)
if err != nil {
return err
}
r.RawValue = v
return nil
}
func (r *RegexpValue) Get() string {
return r.RawValue
}
func (r *RegexpValue) Read(s *Reader) Issue {
l := s.Location()
p := regexp.MustCompile(r.Get())
pos := s.Position()
str := s.Finish()
s.SetPosition(pos)
indexes := p.FindAllIndex([]byte(str), -1)
if len(indexes) == 0 {
return NewIssueWithLocation(fmt.Sprintf("Pattern %v doesn't match.", p.String()), l)
}
s.SetPosition(pos + indexes[0][1])
return nil
}
var _ Value = &ConstValue{}
var _ Value = &RegexpValue{}