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- // Copyright 2016, Google Inc.
- // All rights reserved.
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- package gax
- import (
- "errors"
- "fmt"
- "strings"
- )
- type matcher interface {
- match([]string) (int, error)
- String() string
- }
- type segment struct {
- matcher
- name string
- }
- type labelMatcher string
- func (ls labelMatcher) match(segments []string) (int, error) {
- if len(segments) == 0 {
- return 0, fmt.Errorf("expected %s but no more segments found", ls)
- }
- if segments[0] != string(ls) {
- return 0, fmt.Errorf("expected %s but got %s", ls, segments[0])
- }
- return 1, nil
- }
- func (ls labelMatcher) String() string {
- return string(ls)
- }
- type wildcardMatcher int
- func (wm wildcardMatcher) match(segments []string) (int, error) {
- if len(segments) == 0 {
- return 0, errors.New("no more segments found")
- }
- return 1, nil
- }
- func (wm wildcardMatcher) String() string {
- return "*"
- }
- type pathWildcardMatcher int
- func (pwm pathWildcardMatcher) match(segments []string) (int, error) {
- length := len(segments) - int(pwm)
- if length <= 0 {
- return 0, errors.New("not sufficient segments are supplied for path wildcard")
- }
- return length, nil
- }
- func (pwm pathWildcardMatcher) String() string {
- return "**"
- }
- type ParseError struct {
- Pos int
- Template string
- Message string
- }
- func (pe ParseError) Error() string {
- return fmt.Sprintf("at %d of template '%s', %s", pe.Pos, pe.Template, pe.Message)
- }
- // PathTemplate manages the template to build and match with paths used
- // by API services. It holds a template and variable names in it, and
- // it can extract matched patterns from a path string or build a path
- // string from a binding.
- //
- // See http.proto in github.com/googleapis/googleapis/ for the details of
- // the template syntax.
- type PathTemplate struct {
- segments []segment
- }
- // NewPathTemplate parses a path template, and returns a PathTemplate
- // instance if successful.
- func NewPathTemplate(template string) (*PathTemplate, error) {
- return parsePathTemplate(template)
- }
- // MustCompilePathTemplate is like NewPathTemplate but panics if the
- // expression cannot be parsed. It simplifies safe initialization of
- // global variables holding compiled regular expressions.
- func MustCompilePathTemplate(template string) *PathTemplate {
- pt, err := NewPathTemplate(template)
- if err != nil {
- panic(err)
- }
- return pt
- }
- // Match attempts to match the given path with the template, and returns
- // the mapping of the variable name to the matched pattern string.
- func (pt *PathTemplate) Match(path string) (map[string]string, error) {
- paths := strings.Split(path, "/")
- values := map[string]string{}
- for _, segment := range pt.segments {
- length, err := segment.match(paths)
- if err != nil {
- return nil, err
- }
- if segment.name != "" {
- value := strings.Join(paths[:length], "/")
- if oldValue, ok := values[segment.name]; ok {
- values[segment.name] = oldValue + "/" + value
- } else {
- values[segment.name] = value
- }
- }
- paths = paths[length:]
- }
- if len(paths) != 0 {
- return nil, fmt.Errorf("Trailing path %s remains after the matching", strings.Join(paths, "/"))
- }
- return values, nil
- }
- // Render creates a path string from its template and the binding from
- // the variable name to the value.
- func (pt *PathTemplate) Render(binding map[string]string) (string, error) {
- result := make([]string, 0, len(pt.segments))
- var lastVariableName string
- for _, segment := range pt.segments {
- name := segment.name
- if lastVariableName != "" && name == lastVariableName {
- continue
- }
- lastVariableName = name
- if name == "" {
- result = append(result, segment.String())
- } else if value, ok := binding[name]; ok {
- result = append(result, value)
- } else {
- return "", fmt.Errorf("%s is not found", name)
- }
- }
- built := strings.Join(result, "/")
- return built, nil
- }
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