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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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