blob: 062347f066472b539c6227b0de62b9bcfeab8348 [file] [log] [blame]
/**
* @license
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import {
GrDiffLine,
GrDiffLineType,
FILE,
Highlights,
LineNumber,
} from '../gr-diff/gr-diff-line';
import {
GrDiffGroup,
GrDiffGroupType,
hideInContextControl,
} from '../gr-diff/gr-diff-group';
import {CancelablePromise, makeCancelable} from '../../../scripts/util';
import {DiffContent} from '../../../types/diff';
import {Side} from '../../../constants/constants';
import {debounce, DelayedTask} from '../../../utils/async-util';
import {RenderPreferences} from '../../../api/diff';
import {assertIsDefined} from '../../../utils/common-util';
const WHOLE_FILE = -1;
// visible for testing
export interface State {
lineNums: {
left: number;
right: number;
};
chunkIndex: number;
}
interface ChunkEnd {
offset: number;
keyLocation: boolean;
}
export interface KeyLocations {
left: {[key: string]: boolean};
right: {[key: string]: boolean};
}
/**
* The maximum size for an addition or removal chunk before it is broken down
* into a series of chunks that are this size at most.
*
* Note: The value of 120 is chosen so that it is larger than the default
* asyncThreshold of 64, but feel free to tune this constant to your
* performance needs.
*/
function calcMaxGroupSize(asyncThreshold?: number): number {
if (!asyncThreshold) return 120;
return asyncThreshold * 2;
}
/** Interface for listening to the output of the processor. */
export interface GroupConsumer {
addGroup(group: GrDiffGroup): void;
clearGroups(): void;
}
/**
* Converts the API's `DiffContent`s to `GrDiffGroup`s for rendering.
*
* Glossary:
* - "chunk": A single `DiffContent` as returned by the API.
* - "group": A single `GrDiffGroup` as used for rendering.
* - "common" chunk/group: A chunk/group that should be considered unchanged
* for diffing purposes. This can mean its either actually unchanged, or it
* has only whitespace changes.
* - "key location": A line number and side of the diff that should not be
* collapsed e.g. because a comment is attached to it, or because it was
* provided in the URL and thus should be visible
* - "uncollapsible" chunk/group: A chunk/group that is either not "common",
* or cannot be collapsed because it contains a key location
*
* Here a a number of tasks this processor performs:
* - splitting large chunks to allow more granular async rendering
* - adding a group for the "File" pseudo line that file-level comments can
* be attached to
* - replacing common parts of the diff that are outside the user's
* context setting and do not have comments with a group representing the
* "expand context" widget. This may require splitting a chunk/group so
* that the part that is within the context or has comments is shown, while
* the rest is not.
*/
export class GrDiffProcessor {
context = 3;
consumer?: GroupConsumer;
keyLocations: KeyLocations = {left: {}, right: {}};
private asyncThreshold = 64;
private nextStepHandle: number | null = null;
private processPromise: CancelablePromise<void> | null = null;
// visible for testing
isScrolling?: boolean;
private resetIsScrollingTask?: DelayedTask;
private readonly handleWindowScroll = () => {
this.isScrolling = true;
this.resetIsScrollingTask = debounce(
this.resetIsScrollingTask,
() => (this.isScrolling = false),
50
);
};
/**
* Asynchronously process the diff chunks into groups. As it processes, it
* will splice groups into the `groups` property of the component.
*
* @return A promise that resolves with an
* array of GrDiffGroups when the diff is completely processed.
*/
process(chunks: DiffContent[], isBinary: boolean) {
// Cancel any still running process() calls, because they append to the
// same groups field.
this.cancel();
window.addEventListener('scroll', this.handleWindowScroll);
assertIsDefined(this.consumer, 'consumer');
this.consumer.clearGroups();
this.consumer.addGroup(this.makeGroup('LOST'));
this.consumer.addGroup(this.makeGroup(FILE));
// If it's a binary diff, we won't be rendering hunks of text differences
// so finish processing.
if (isBinary) {
return Promise.resolve();
}
// TODO: Canceling this promise does not help much. `nextStep` will continue
// to be scheduled anyway. So either just remove the cancelable promise, so
// future programmers are not fooled about this promise can do. Or fix the
// scheduling of `nextStep` such that cancellation is taken into account.
// The easiest approach is likely to just not re-use the processor for
// multiple processing passes. There is no benefit from doing so.
this.processPromise = makeCancelable(
new Promise(resolve => {
const state = {
lineNums: {left: 0, right: 0},
chunkIndex: 0,
};
chunks = this.splitLargeChunks(chunks);
chunks = this.splitCommonChunksWithKeyLocations(chunks);
let currentBatch = 0;
const nextStep = () => {
if (this.isScrolling) {
this.nextStepHandle = window.setTimeout(nextStep, 100);
return;
}
// If we are done, resolve the promise.
if (state.chunkIndex >= chunks.length) {
resolve();
this.nextStepHandle = null;
return;
}
// Process the next chunk and incorporate the result.
const stateUpdate = this.processNext(state, chunks);
for (const group of stateUpdate.groups) {
assertIsDefined(this.consumer, 'consumer');
this.consumer.addGroup(group);
currentBatch += group.lines.length;
}
state.lineNums.left += stateUpdate.lineDelta.left;
state.lineNums.right += stateUpdate.lineDelta.right;
// Increment the index and recurse.
state.chunkIndex = stateUpdate.newChunkIndex;
if (currentBatch >= this.asyncThreshold) {
currentBatch = 0;
this.nextStepHandle = window.setTimeout(nextStep, 1);
} else {
nextStep.call(this);
}
};
nextStep.call(this);
})
);
return this.processPromise.finally(() => {
this.processPromise = null;
window.removeEventListener('scroll', this.handleWindowScroll);
});
}
/**
* Cancel any jobs that are running.
*/
cancel() {
if (this.nextStepHandle !== null) {
window.clearTimeout(this.nextStepHandle);
this.nextStepHandle = null;
}
if (this.processPromise) {
this.processPromise.cancel();
}
window.removeEventListener('scroll', this.handleWindowScroll);
}
/**
* Process the next uncollapsible chunk, or the next collapsible chunks.
*/
// visible for testing
processNext(state: State, chunks: DiffContent[]) {
const firstUncollapsibleChunkIndex = this.firstUncollapsibleChunkIndex(
chunks,
state.chunkIndex
);
if (firstUncollapsibleChunkIndex === state.chunkIndex) {
const chunk = chunks[state.chunkIndex];
return {
lineDelta: {
left: this.linesLeft(chunk).length,
right: this.linesRight(chunk).length,
},
groups: [
this.chunkToGroup(
chunk,
state.lineNums.left + 1,
state.lineNums.right + 1
),
],
newChunkIndex: state.chunkIndex + 1,
};
}
return this.processCollapsibleChunks(
state,
chunks,
firstUncollapsibleChunkIndex
);
}
private linesLeft(chunk: DiffContent) {
return chunk.ab || chunk.a || [];
}
private linesRight(chunk: DiffContent) {
return chunk.ab || chunk.b || [];
}
private firstUncollapsibleChunkIndex(chunks: DiffContent[], offset: number) {
let chunkIndex = offset;
while (
chunkIndex < chunks.length &&
this.isCollapsibleChunk(chunks[chunkIndex])
) {
chunkIndex++;
}
return chunkIndex;
}
private isCollapsibleChunk(chunk: DiffContent) {
return (chunk.ab || chunk.common || chunk.skip) && !chunk.keyLocation;
}
/**
* Process a stretch of collapsible chunks.
*
* Outputs up to three groups:
* 1) Visible context before the hidden common code, unless it's the
* very beginning of the file.
* 2) Context hidden behind a context bar, unless empty.
* 3) Visible context after the hidden common code, unless it's the very
* end of the file.
*/
private processCollapsibleChunks(
state: State,
chunks: DiffContent[],
firstUncollapsibleChunkIndex: number
) {
const collapsibleChunks = chunks.slice(
state.chunkIndex,
firstUncollapsibleChunkIndex
);
const lineCount = collapsibleChunks.reduce(
(sum, chunk) => sum + this.commonChunkLength(chunk),
0
);
let groups = this.chunksToGroups(
collapsibleChunks,
state.lineNums.left + 1,
state.lineNums.right + 1
);
const hasSkippedGroup = !!groups.find(g => g.skip);
if (this.context !== WHOLE_FILE || hasSkippedGroup) {
const contextNumLines = this.context > 0 ? this.context : 0;
const hiddenStart = state.chunkIndex === 0 ? 0 : contextNumLines;
const hiddenEnd =
lineCount -
(firstUncollapsibleChunkIndex === chunks.length ? 0 : this.context);
groups = hideInContextControl(groups, hiddenStart, hiddenEnd);
}
return {
lineDelta: {
left: lineCount,
right: lineCount,
},
groups,
newChunkIndex: firstUncollapsibleChunkIndex,
};
}
private commonChunkLength(chunk: DiffContent) {
if (chunk.skip) {
return chunk.skip;
}
console.assert(!!chunk.ab || !!chunk.common);
console.assert(
!chunk.a || (!!chunk.b && chunk.a.length === chunk.b.length),
'common chunk needs same number of a and b lines: ',
chunk
);
return this.linesLeft(chunk).length;
}
private chunksToGroups(
chunks: DiffContent[],
offsetLeft: number,
offsetRight: number
): GrDiffGroup[] {
return chunks.map(chunk => {
const group = this.chunkToGroup(chunk, offsetLeft, offsetRight);
const chunkLength = this.commonChunkLength(chunk);
offsetLeft += chunkLength;
offsetRight += chunkLength;
return group;
});
}
private chunkToGroup(
chunk: DiffContent,
offsetLeft: number,
offsetRight: number
): GrDiffGroup {
const type =
chunk.ab || chunk.skip ? GrDiffGroupType.BOTH : GrDiffGroupType.DELTA;
const lines = this.linesFromChunk(chunk, offsetLeft, offsetRight);
const options = {
moveDetails: chunk.move_details,
dueToRebase: !!chunk.due_to_rebase,
ignoredWhitespaceOnly: !!chunk.common,
keyLocation: !!chunk.keyLocation,
};
if (chunk.skip !== undefined) {
return new GrDiffGroup({
type,
skip: chunk.skip,
offsetLeft,
offsetRight,
...options,
});
} else {
return new GrDiffGroup({
type,
lines,
...options,
});
}
}
private linesFromChunk(
chunk: DiffContent,
offsetLeft: number,
offsetRight: number
) {
if (chunk.ab) {
return chunk.ab.map((row, i) =>
this.lineFromRow(GrDiffLineType.BOTH, offsetLeft, offsetRight, row, i)
);
}
let lines: GrDiffLine[] = [];
if (chunk.a) {
// Avoiding a.push(...b) because that causes callstack overflows for
// large b, which can occur when large files are added removed.
lines = lines.concat(
this.linesFromRows(
GrDiffLineType.REMOVE,
chunk.a,
offsetLeft,
chunk.edit_a
)
);
}
if (chunk.b) {
// Avoiding a.push(...b) because that causes callstack overflows for
// large b, which can occur when large files are added removed.
lines = lines.concat(
this.linesFromRows(
GrDiffLineType.ADD,
chunk.b,
offsetRight,
chunk.edit_b
)
);
}
return lines;
}
// visible for testing
linesFromRows(
lineType: GrDiffLineType,
rows: string[],
offset: number,
intralineInfos?: number[][]
): GrDiffLine[] {
const grDiffHighlights = intralineInfos
? this.convertIntralineInfos(rows, intralineInfos)
: undefined;
return rows.map((row, i) =>
this.lineFromRow(lineType, offset, offset, row, i, grDiffHighlights)
);
}
private lineFromRow(
type: GrDiffLineType,
offsetLeft: number,
offsetRight: number,
row: string,
i: number,
highlights?: Highlights[]
): GrDiffLine {
const line = new GrDiffLine(type);
line.text = row;
if (type !== GrDiffLineType.ADD) line.beforeNumber = offsetLeft + i;
if (type !== GrDiffLineType.REMOVE) line.afterNumber = offsetRight + i;
if (highlights) {
line.hasIntralineInfo = true;
line.highlights = highlights.filter(hl => hl.contentIndex === i);
} else {
line.hasIntralineInfo = false;
}
return line;
}
private makeGroup(number: LineNumber) {
const line = new GrDiffLine(GrDiffLineType.BOTH);
line.beforeNumber = number;
line.afterNumber = number;
return new GrDiffGroup({type: GrDiffGroupType.BOTH, lines: [line]});
}
/**
* Split chunks into smaller chunks of the same kind.
*
* This is done to prevent doing too much work on the main thread in one
* uninterrupted rendering step, which would make the browser unresponsive.
*
* Note that in the case of unmodified chunks, we only split chunks if the
* context is set to file (because otherwise they are split up further down
* the processing into the visible and hidden context), and only split it
* into 2 chunks, one max sized one and the rest (for reasons that are
* unclear to me).
*
* @param chunks Chunks as returned from the server
* @return Finer grained chunks.
*/
// visible for testing
splitLargeChunks(chunks: DiffContent[]): DiffContent[] {
const newChunks = [];
for (const chunk of chunks) {
if (!chunk.ab) {
for (const subChunk of this.breakdownChunk(chunk)) {
newChunks.push(subChunk);
}
continue;
}
// If the context is set to "whole file", then break down the shared
// chunks so they can be rendered incrementally. Note: this is not
// enabled for any other context preference because manipulating the
// chunks in this way violates assumptions by the context grouper logic.
const MAX_GROUP_SIZE = calcMaxGroupSize(this.asyncThreshold);
if (this.context === -1 && chunk.ab.length > MAX_GROUP_SIZE * 2) {
// Split large shared chunks in two, where the first is the maximum
// group size.
newChunks.push({ab: chunk.ab.slice(0, MAX_GROUP_SIZE)});
newChunks.push({ab: chunk.ab.slice(MAX_GROUP_SIZE)});
} else {
newChunks.push(chunk);
}
}
return newChunks;
}
/**
* In order to show key locations, such as comments, out of the bounds of
* the selected context, treat them as separate chunks within the model so
* that the content (and context surrounding it) renders correctly.
*
* @param chunks DiffContents as returned from server.
* @return Finer grained DiffContents.
*/
// visible for testing
splitCommonChunksWithKeyLocations(chunks: DiffContent[]): DiffContent[] {
const result = [];
let leftLineNum = 1;
let rightLineNum = 1;
for (const chunk of chunks) {
// If it isn't a common chunk, append it as-is and update line numbers.
if (!chunk.ab && !chunk.skip && !chunk.common) {
if (chunk.a) {
leftLineNum += chunk.a.length;
}
if (chunk.b) {
rightLineNum += chunk.b.length;
}
result.push(chunk);
continue;
}
if (chunk.common && chunk.a!.length !== chunk.b!.length) {
throw new Error(
'DiffContent with common=true must always have equal length'
);
}
const numLines = this.commonChunkLength(chunk);
const chunkEnds = this.findChunkEndsAtKeyLocations(
numLines,
leftLineNum,
rightLineNum
);
leftLineNum += numLines;
rightLineNum += numLines;
if (chunk.skip) {
result.push({
...chunk,
skip: chunk.skip,
keyLocation: false,
});
} else if (chunk.ab) {
result.push(
...this.splitAtChunkEnds(chunk.ab, chunkEnds).map(
({lines, keyLocation}) => {
return {
...chunk,
ab: lines,
keyLocation,
};
}
)
);
} else if (chunk.common) {
const aChunks = this.splitAtChunkEnds(chunk.a!, chunkEnds);
const bChunks = this.splitAtChunkEnds(chunk.b!, chunkEnds);
result.push(
...aChunks.map(({lines, keyLocation}, i) => {
return {
...chunk,
a: lines,
b: bChunks[i].lines,
keyLocation,
};
})
);
}
}
return result;
}
/**
* @return Offsets of the new chunk ends, including whether it's a key
* location.
*/
private findChunkEndsAtKeyLocations(
numLines: number,
leftOffset: number,
rightOffset: number
): ChunkEnd[] {
const result = [];
let lastChunkEnd = 0;
for (let i = 0; i < numLines; i++) {
// If this line should not be collapsed.
if (
this.keyLocations[Side.LEFT][leftOffset + i] ||
this.keyLocations[Side.RIGHT][rightOffset + i]
) {
// If any lines have been accumulated into the chunk leading up to
// this non-collapse line, then add them as a chunk and start a new
// one.
if (i > lastChunkEnd) {
result.push({offset: i, keyLocation: false});
lastChunkEnd = i;
}
// Add the non-collapse line as its own chunk.
result.push({offset: i + 1, keyLocation: true});
}
}
if (numLines > lastChunkEnd) {
result.push({offset: numLines, keyLocation: false});
}
return result;
}
private splitAtChunkEnds(lines: string[], chunkEnds: ChunkEnd[]) {
const result = [];
let lastChunkEndOffset = 0;
for (const {offset, keyLocation} of chunkEnds) {
if (lastChunkEndOffset === offset) continue;
result.push({
lines: lines.slice(lastChunkEndOffset, offset),
keyLocation,
});
lastChunkEndOffset = offset;
}
return result;
}
/**
* Converts `IntralineInfo`s return by the API to `GrLineHighlights` used
* for rendering.
*/
// visible for testing
convertIntralineInfos(
rows: string[],
intralineInfos: number[][]
): Highlights[] {
let rowIndex = 0;
let idx = 0;
const normalized = [];
for (const [skipLength, markLength] of intralineInfos) {
let line = rows[rowIndex] + '\n';
let j = 0;
while (j < skipLength) {
if (idx === line.length) {
idx = 0;
line = rows[++rowIndex] + '\n';
continue;
}
idx++;
j++;
}
let lineHighlight: Highlights = {
contentIndex: rowIndex,
startIndex: idx,
};
j = 0;
while (line && j < markLength) {
if (idx === line.length) {
idx = 0;
line = rows[++rowIndex] + '\n';
normalized.push(lineHighlight);
lineHighlight = {
contentIndex: rowIndex,
startIndex: idx,
};
continue;
}
idx++;
j++;
}
lineHighlight.endIndex = idx;
normalized.push(lineHighlight);
}
return normalized;
}
/**
* If a group is an addition or a removal, break it down into smaller groups
* of that type using the MAX_GROUP_SIZE. If the group is a shared chunk
* or a delta it is returned as the single element of the result array.
*/
// visible for testing
breakdownChunk(chunk: DiffContent): DiffContent[] {
let key: 'a' | 'b' | 'ab' | null = null;
const {a, b, ab, move_details} = chunk;
if (a?.length && !b?.length) {
key = 'a';
} else if (b?.length && !a?.length) {
key = 'b';
} else if (ab?.length) {
key = 'ab';
}
// Move chunks should not be divided because of move label
// positioned in the top of the chunk
if (!key || move_details) {
return [chunk];
}
const MAX_GROUP_SIZE = calcMaxGroupSize(this.asyncThreshold);
return this.breakdown(chunk[key]!, MAX_GROUP_SIZE).map(subChunkLines => {
const subChunk: DiffContent = {};
subChunk[key!] = subChunkLines;
if (chunk.due_to_rebase) {
subChunk.due_to_rebase = true;
}
if (chunk.move_details) {
subChunk.move_details = chunk.move_details;
}
return subChunk;
});
}
/**
* Given an array and a size, return an array of arrays where no inner array
* is larger than that size, preserving the original order.
*/
// visible for testing
breakdown<T>(array: T[], size: number): T[][] {
if (!array.length) {
return [];
}
if (array.length < size) {
return [array];
}
const head = array.slice(0, array.length - size);
const tail = array.slice(array.length - size);
return this.breakdown(head, size).concat([tail]);
}
updateRenderPrefs(renderPrefs: RenderPreferences) {
if (renderPrefs.num_lines_rendered_at_once) {
this.asyncThreshold = renderPrefs.num_lines_rendered_at_once;
}
}
}