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Diffstat (limited to 'src/lib/strings/rich-text.ts')
| -rw-r--r-- | src/lib/strings/rich-text.ts | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/src/lib/strings/rich-text.ts b/src/lib/strings/rich-text.ts new file mode 100644 index 000000000..1df2144e0 --- /dev/null +++ b/src/lib/strings/rich-text.ts @@ -0,0 +1,216 @@ +/* += Rich Text Manipulation + +When we sanitize rich text, we have to update the entity indices as the +text is modified. This can be modeled as inserts() and deletes() of the +rich text string. The possible scenarios are outlined below, along with +their expected behaviors. + +NOTE: Slices are start inclusive, end exclusive + +== richTextInsert() + +Target string: + + 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l o w o r l d // string value + ^-------^ // target slice {start: 2, end: 7} + +Scenarios: + +A: ^ // insert "test" at 0 +B: ^ // insert "test" at 4 +C: ^ // insert "test" at 8 + +A = before -> move both by num added +B = inner -> move end by num added +C = after -> noop + +Results: + +A: 0 1 2 3 4 5 6 7 8 910 // string indices + t e s t h e l l o w // string value + ^-------^ // target slice {start: 6, end: 11} + +B: 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l t e s t o w // string value + ^---------------^ // target slice {start: 2, end: 11} + +C: 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l o w o t e s // string value + ^-------^ // target slice {start: 2, end: 7} + +== richTextDelete() + +Target string: + + 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l o w o r l d // string value + ^-------^ // target slice {start: 2, end: 7} + +Scenarios: + +A: ^---------------^ // remove slice {start: 0, end: 9} +B: ^-----^ // remove slice {start: 7, end: 11} +C: ^-----------^ // remove slice {start: 4, end: 11} +D: ^-^ // remove slice {start: 3, end: 5} +E: ^-----^ // remove slice {start: 1, end: 5} +F: ^-^ // remove slice {start: 0, end: 2} + +A = entirely outer -> delete slice +B = entirely after -> noop +C = partially after -> move end to remove-start +D = entirely inner -> move end by num removed +E = partially before -> move start to remove-start index, move end by num removed +F = entirely before -> move both by num removed + +Results: + +A: 0 1 2 3 4 5 6 7 8 910 // string indices + l d // string value + // target slice (deleted) + +B: 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l o w // string value + ^-------^ // target slice {start: 2, end: 7} + +C: 0 1 2 3 4 5 6 7 8 910 // string indices + h e l l // string value + ^-^ // target slice {start: 2, end: 4} + +D: 0 1 2 3 4 5 6 7 8 910 // string indices + h e l w o r l d // string value + ^---^ // target slice {start: 2, end: 5} + +E: 0 1 2 3 4 5 6 7 8 910 // string indices + h w o r l d // string value + ^-^ // target slice {start: 1, end: 3} + +F: 0 1 2 3 4 5 6 7 8 910 // string indices + l l o w o r l d // string value + ^-------^ // target slice {start: 0, end: 5} + */ + +import cloneDeep from 'lodash.clonedeep' +import {AppBskyFeedPost} from '@atproto/api' +import {removeExcessNewlines} from './rich-text-sanitize' + +export type Entity = AppBskyFeedPost.Entity +export interface RichTextOpts { + cleanNewlines?: boolean +} + +export class RichText { + constructor( + public text: string, + public entities?: Entity[], + opts?: RichTextOpts, + ) { + if (opts?.cleanNewlines) { + removeExcessNewlines(this).copyInto(this) + } + } + + clone() { + return new RichText(this.text, cloneDeep(this.entities)) + } + + copyInto(target: RichText) { + target.text = this.text + target.entities = cloneDeep(this.entities) + } + + insert(insertIndex: number, insertText: string) { + this.text = + this.text.slice(0, insertIndex) + + insertText + + this.text.slice(insertIndex) + + if (!this.entities?.length) { + return this + } + + const numCharsAdded = insertText.length + for (const ent of this.entities) { + // see comment at top of file for labels of each scenario + // scenario A (before) + if (insertIndex <= ent.index.start) { + // move both by num added + ent.index.start += numCharsAdded + ent.index.end += numCharsAdded + } + // scenario B (inner) + else if (insertIndex >= ent.index.start && insertIndex < ent.index.end) { + // move end by num added + ent.index.end += numCharsAdded + } + // scenario C (after) + // noop + } + return this + } + + delete(removeStartIndex: number, removeEndIndex: number) { + this.text = + this.text.slice(0, removeStartIndex) + this.text.slice(removeEndIndex) + + if (!this.entities?.length) { + return this + } + + const numCharsRemoved = removeEndIndex - removeStartIndex + for (const ent of this.entities) { + // see comment at top of file for labels of each scenario + // scenario A (entirely outer) + if ( + removeStartIndex <= ent.index.start && + removeEndIndex >= ent.index.end + ) { + // delete slice (will get removed in final pass) + ent.index.start = 0 + ent.index.end = 0 + } + // scenario B (entirely after) + else if (removeStartIndex > ent.index.end) { + // noop + } + // scenario C (partially after) + else if ( + removeStartIndex > ent.index.start && + removeStartIndex <= ent.index.end && + removeEndIndex > ent.index.end + ) { + // move end to remove start + ent.index.end = removeStartIndex + } + // scenario D (entirely inner) + else if ( + removeStartIndex >= ent.index.start && + removeEndIndex <= ent.index.end + ) { + // move end by num removed + ent.index.end -= numCharsRemoved + } + // scenario E (partially before) + else if ( + removeStartIndex < ent.index.start && + removeEndIndex >= ent.index.start && + removeEndIndex <= ent.index.end + ) { + // move start to remove-start index, move end by num removed + ent.index.start = removeStartIndex + ent.index.end -= numCharsRemoved + } + // scenario F (entirely before) + else if (removeEndIndex < ent.index.start) { + // move both by num removed + ent.index.start -= numCharsRemoved + ent.index.end -= numCharsRemoved + } + } + + // filter out any entities that were made irrelevant + this.entities = this.entities.filter(ent => ent.index.start < ent.index.end) + return this + } +} |