mirror of
https://github.com/crazy-max/diun.git
synced 2024-12-23 03:48:00 +00:00
123 lines
3.6 KiB
Go
123 lines
3.6 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Package protopath provides functionality for
|
|
// representing a sequence of protobuf reflection operations on a message.
|
|
package protopath
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"google.golang.org/protobuf/internal/msgfmt"
|
|
"google.golang.org/protobuf/reflect/protoreflect"
|
|
)
|
|
|
|
// NOTE: The Path and Values are separate types here since there are use cases
|
|
// where you would like to "address" some value in a message with just the path
|
|
// and don't have the value information available.
|
|
//
|
|
// This is different from how github.com/google/go-cmp/cmp.Path operates,
|
|
// which combines both path and value information together.
|
|
// Since the cmp package itself is the only one ever constructing a cmp.Path,
|
|
// it will always have the value available.
|
|
|
|
// Path is a sequence of protobuf reflection steps applied to some root
|
|
// protobuf message value to arrive at the current value.
|
|
// The first step must be a [Root] step.
|
|
type Path []Step
|
|
|
|
// TODO: Provide a Parse function that parses something similar to or
|
|
// perhaps identical to the output of Path.String.
|
|
|
|
// Index returns the ith step in the path and supports negative indexing.
|
|
// A negative index starts counting from the tail of the Path such that -1
|
|
// refers to the last step, -2 refers to the second-to-last step, and so on.
|
|
// It returns a zero Step value if the index is out-of-bounds.
|
|
func (p Path) Index(i int) Step {
|
|
if i < 0 {
|
|
i = len(p) + i
|
|
}
|
|
if i < 0 || i >= len(p) {
|
|
return Step{}
|
|
}
|
|
return p[i]
|
|
}
|
|
|
|
// String returns a structured representation of the path
|
|
// by concatenating the string representation of every path step.
|
|
func (p Path) String() string {
|
|
var b []byte
|
|
for _, s := range p {
|
|
b = s.appendString(b)
|
|
}
|
|
return string(b)
|
|
}
|
|
|
|
// Values is a Path paired with a sequence of values at each step.
|
|
// The lengths of [Values.Path] and [Values.Values] must be identical.
|
|
// The first step must be a [Root] step and
|
|
// the first value must be a concrete message value.
|
|
type Values struct {
|
|
Path Path
|
|
Values []protoreflect.Value
|
|
}
|
|
|
|
// Len reports the length of the path and values.
|
|
// If the path and values have differing length, it returns the minimum length.
|
|
func (p Values) Len() int {
|
|
n := len(p.Path)
|
|
if n > len(p.Values) {
|
|
n = len(p.Values)
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Index returns the ith step and value and supports negative indexing.
|
|
// A negative index starts counting from the tail of the Values such that -1
|
|
// refers to the last pair, -2 refers to the second-to-last pair, and so on.
|
|
func (p Values) Index(i int) (out struct {
|
|
Step Step
|
|
Value protoreflect.Value
|
|
}) {
|
|
// NOTE: This returns a single struct instead of two return values so that
|
|
// callers can make use of the the value in an expression:
|
|
// vs.Index(i).Value.Interface()
|
|
n := p.Len()
|
|
if i < 0 {
|
|
i = n + i
|
|
}
|
|
if i < 0 || i >= n {
|
|
return out
|
|
}
|
|
out.Step = p.Path[i]
|
|
out.Value = p.Values[i]
|
|
return out
|
|
}
|
|
|
|
// String returns a humanly readable representation of the path and last value.
|
|
// Do not depend on the output being stable.
|
|
//
|
|
// For example:
|
|
//
|
|
// (path.to.MyMessage).list_field[5].map_field["hello"] = {hello: "world"}
|
|
func (p Values) String() string {
|
|
n := p.Len()
|
|
if n == 0 {
|
|
return ""
|
|
}
|
|
|
|
// Determine the field descriptor associated with the last step.
|
|
var fd protoreflect.FieldDescriptor
|
|
last := p.Index(-1)
|
|
switch last.Step.kind {
|
|
case FieldAccessStep:
|
|
fd = last.Step.FieldDescriptor()
|
|
case MapIndexStep, ListIndexStep:
|
|
fd = p.Index(-2).Step.FieldDescriptor()
|
|
}
|
|
|
|
// Format the full path with the last value.
|
|
return fmt.Sprintf("%v = %v", p.Path[:n], msgfmt.FormatValue(last.Value, fd))
|
|
}
|