/
parse.go
111 lines (90 loc) · 2.26 KB
/
parse.go
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// Copyright (c) 2016 Matt Ho <matt.ho@gmail.com>
//
// 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 jq
import (
"fmt"
"regexp"
"strconv"
"strings"
)
var (
reArray = regexp.MustCompile(`^\s*\[\s*(?:(\d+))?\s*(?:(:))?\s*(?:(\d+))?\s*\]\s*$`)
)
// Must is a convenience method similar to template.Must
func Must(op Op, err error) Op {
if err != nil {
panic(fmt.Errorf("unable to parse selector; %v", err.Error()))
}
return op
}
// Parse takes a string representation of a selector and returns the corresponding Op definition
func Parse(selector string) (Op, error) {
segments := strings.Split(selector, ".")
ops := make([]Op, 0, len(segments))
for _, segment := range segments {
key := strings.TrimSpace(segment)
if key == "" {
continue
}
if op, ok := parseArray(key); ok {
ops = append(ops, op)
continue
}
ops = append(ops, Dot(key))
}
return Chain(ops...), nil
}
func parseArray(key string) (Op, bool) {
match := FindIndices(key)
if len(match) == 0 {
return nil, false
}
matches := match[0]
if matches[1]+matches[2]+matches[3] == "" {
return From(0), true
}
if matches[2] == "" {
idx, err := strconv.Atoi(matches[1])
if err != nil {
return nil, false
}
return Index(idx), true
}
if matches[1] == "" {
to, err := strconv.Atoi(matches[3])
if err != nil {
return nil, false
}
return To(to), true
}
if matches[3] == "" {
from, err := strconv.Atoi(matches[1])
if err != nil {
return nil, false
}
return From(from), true
}
from, err := strconv.Atoi(matches[1])
if err != nil {
return nil, false
}
to, err := strconv.Atoi(matches[3])
if err != nil {
return nil, false
}
return Range(from, to), true
}
func FindIndices(key string) [][]string {
return reArray.FindAllStringSubmatch(key, -1)
}