Colin Cross | 8e0c511 | 2015-01-23 14:15:10 -0800 | [diff] [blame] | 1 | // Copyright 2014 Google Inc. All rights reserved. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 15 | package parser |
| 16 | |
Colin Cross | 957b39c | 2018-03-21 18:10:01 -0700 | [diff] [blame] | 17 | import ( |
| 18 | "fmt" |
| 19 | "io" |
| 20 | "math" |
| 21 | "sort" |
| 22 | ) |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 23 | |
Colin Cross | e32cc80 | 2016-06-07 12:28:16 -0700 | [diff] [blame] | 24 | func AddStringToList(list *List, s string) (modified bool) { |
| 25 | for _, v := range list.Values { |
| 26 | if v.Type() != StringType { |
| 27 | panic(fmt.Errorf("expected string in list, got %s", v.Type())) |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 28 | } |
| 29 | |
Colin Cross | e32cc80 | 2016-06-07 12:28:16 -0700 | [diff] [blame] | 30 | if sv, ok := v.(*String); ok && sv.Value == s { |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 31 | // string already exists |
| 32 | return false |
| 33 | } |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 34 | } |
| 35 | |
Colin Cross | e32cc80 | 2016-06-07 12:28:16 -0700 | [diff] [blame] | 36 | list.Values = append(list.Values, &String{ |
| 37 | LiteralPos: list.RBracePos, |
| 38 | Value: s, |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 39 | }) |
| 40 | |
| 41 | return true |
| 42 | } |
| 43 | |
Colin Cross | e32cc80 | 2016-06-07 12:28:16 -0700 | [diff] [blame] | 44 | func RemoveStringFromList(list *List, s string) (modified bool) { |
| 45 | for i, v := range list.Values { |
| 46 | if v.Type() != StringType { |
| 47 | panic(fmt.Errorf("expected string in list, got %s", v.Type())) |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 48 | } |
| 49 | |
Colin Cross | e32cc80 | 2016-06-07 12:28:16 -0700 | [diff] [blame] | 50 | if sv, ok := v.(*String); ok && sv.Value == s { |
| 51 | list.Values = append(list.Values[:i], list.Values[i+1:]...) |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 52 | return true |
| 53 | } |
Colin Cross | 41c397a | 2015-01-12 17:43:04 -0800 | [diff] [blame] | 54 | } |
| 55 | |
| 56 | return false |
| 57 | } |
Colin Cross | 957b39c | 2018-03-21 18:10:01 -0700 | [diff] [blame] | 58 | |
| 59 | // A Patch represents a region of a text buffer to be replaced [Start, End) and its Replacement |
| 60 | type Patch struct { |
| 61 | Start, End int |
| 62 | Replacement string |
| 63 | } |
| 64 | |
| 65 | // A PatchList is a list of sorted, non-overlapping Patch objects |
| 66 | type PatchList []Patch |
| 67 | |
| 68 | type PatchOverlapError error |
| 69 | |
| 70 | // Add adds a Patch to a PatchList. It returns a PatchOverlapError if the patch cannot be added. |
| 71 | func (list *PatchList) Add(start, end int, replacement string) error { |
| 72 | patch := Patch{start, end, replacement} |
| 73 | if patch.Start > patch.End { |
| 74 | return fmt.Errorf("invalid patch, start %d is after end %d", patch.Start, patch.End) |
| 75 | } |
| 76 | for _, p := range *list { |
| 77 | if (patch.Start >= p.Start && patch.Start < p.End) || |
| 78 | (patch.End >= p.Start && patch.End < p.End) || |
| 79 | (p.Start >= patch.Start && p.Start < patch.End) || |
| 80 | (p.Start == patch.Start && p.End == patch.End) { |
| 81 | return PatchOverlapError(fmt.Errorf("new patch %d-%d overlaps with existing patch %d-%d", |
| 82 | patch.Start, patch.End, p.Start, p.End)) |
| 83 | } |
| 84 | } |
| 85 | *list = append(*list, patch) |
| 86 | list.sort() |
| 87 | return nil |
| 88 | } |
| 89 | |
| 90 | func (list *PatchList) sort() { |
| 91 | sort.SliceStable(*list, |
| 92 | func(i, j int) bool { |
| 93 | return (*list)[i].Start < (*list)[j].Start |
| 94 | }) |
| 95 | } |
| 96 | |
| 97 | // Apply applies all the Patch objects in PatchList to the data from an input ReaderAt to an output Writer. |
| 98 | func (list *PatchList) Apply(in io.ReaderAt, out io.Writer) error { |
| 99 | var offset int64 |
| 100 | for _, patch := range *list { |
| 101 | toWrite := int64(patch.Start) - offset |
| 102 | written, err := io.Copy(out, io.NewSectionReader(in, offset, toWrite)) |
| 103 | if err != nil { |
| 104 | return err |
| 105 | } |
| 106 | offset += toWrite |
| 107 | if written != toWrite { |
| 108 | return fmt.Errorf("unexpected EOF at %d", offset) |
| 109 | } |
| 110 | |
| 111 | _, err = io.WriteString(out, patch.Replacement) |
| 112 | if err != nil { |
| 113 | return err |
| 114 | } |
| 115 | |
| 116 | offset += int64(patch.End - patch.Start) |
| 117 | } |
| 118 | _, err := io.Copy(out, io.NewSectionReader(in, offset, math.MaxInt64-offset)) |
| 119 | return err |
| 120 | } |