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import type {
Completion,
CompletionContext,
CompletionResult,
} from '@codemirror/autocomplete';
import type { ChangeSet, Transaction } from '@codemirror/state';
import escapeStringRegexp from 'escape-string-regexp';
import { getLogger } from '../logging';
import type { UpdateService } from './UpdateService';
import type { IContentAssistEntry } from './xtextServiceResults';
const PROPOSALS_LIMIT = 1000;
const IDENTIFIER_REGEXP_STR = '[a-zA-Z0-9_]*';
const log = getLogger('xtext.ContentAssistService');
function createCompletion(entry: IContentAssistEntry): Completion {
let boost;
switch (entry.kind) {
case 'KEYWORD':
boost = -99;
break;
case 'TEXT':
case 'SNIPPET':
boost = -90;
break;
default:
boost = 0;
break;
}
return {
label: entry.proposal,
detail: entry.description,
info: entry.documentation,
type: entry.kind?.toLowerCase(),
boost,
};
}
function computeSpan(prefix: string, entryCount: number) {
const escapedPrefix = escapeStringRegexp(prefix);
if (entryCount < PROPOSALS_LIMIT) {
// Proposals with the current prefix fit the proposals limit.
// We can filter client side as long as the current prefix is preserved.
return new RegExp(`^${escapedPrefix}${IDENTIFIER_REGEXP_STR}$`);
}
// The current prefix overflows the proposals limits,
// so we have to fetch the completions again on the next keypress.
// Hopefully, it'll return a shorter list and we'll be able to filter client side.
return new RegExp(`^${escapedPrefix}$`);
}
export class ContentAssistService {
updateService: UpdateService;
lastCompletion: CompletionResult | null = null;
constructor(updateService: UpdateService) {
this.updateService = updateService;
}
onTransaction(transaction: Transaction): void {
if (this.shouldInvalidateCachedCompletion(transaction.changes)) {
this.lastCompletion = null;
}
}
async contentAssist(context: CompletionContext): Promise<CompletionResult> {
const tokenBefore = context.tokenBefore(['QualifiedName']);
let range: { from: number, to: number };
let prefix = '';
if (tokenBefore === null) {
if (!context.explicit) {
return {
from: context.pos,
options: [],
};
}
range = {
from: context.pos,
to: context.pos,
};
prefix = '';
} else {
range = {
from: tokenBefore.from,
to: tokenBefore.to,
};
const prefixLength = context.pos - tokenBefore.from;
if (prefixLength > 0) {
prefix = tokenBefore.text.substring(0, context.pos - tokenBefore.from);
}
}
if (!context.explicit && this.shouldReturnCachedCompletion(tokenBefore)) {
log.trace('Returning cached completion result');
// Postcondition of `shouldReturnCachedCompletion`: `lastCompletion !== null`
return {
...this.lastCompletion as CompletionResult,
...range,
};
}
this.lastCompletion = null;
const entries = await this.updateService.fetchContentAssist({
resource: this.updateService.resourceName,
serviceType: 'assist',
caretOffset: context.pos,
proposalsLimit: PROPOSALS_LIMIT,
}, context);
if (context.aborted) {
return {
...range,
options: [],
};
}
const options: Completion[] = [];
entries.forEach((entry) => {
options.push(createCompletion(entry));
});
log.debug('Fetched', options.length, 'completions from server');
this.lastCompletion = {
...range,
options,
span: computeSpan(prefix, entries.length),
};
return this.lastCompletion;
}
private shouldReturnCachedCompletion(
token: { from: number, to: number, text: string } | null,
) {
if (token === null || this.lastCompletion === null) {
return false;
}
const { from, to, text } = token;
const { from: lastFrom, to: lastTo, span } = this.lastCompletion;
if (!lastTo) {
return true;
}
const [transformedFrom, transformedTo] = this.mapRangeInclusive(lastFrom, lastTo);
return from >= transformedFrom && to <= transformedTo && span && span.exec(text);
}
private shouldInvalidateCachedCompletion(changes: ChangeSet) {
if (changes.empty || this.lastCompletion === null) {
return false;
}
const { from: lastFrom, to: lastTo } = this.lastCompletion;
if (!lastTo) {
return true;
}
const [transformedFrom, transformedTo] = this.mapRangeInclusive(lastFrom, lastTo);
let invalidate = false;
changes.iterChangedRanges((fromA, toA) => {
if (fromA < transformedFrom || toA > transformedTo) {
invalidate = true;
}
});
return invalidate;
}
private mapRangeInclusive(lastFrom: number, lastTo: number): [number, number] {
const changes = this.updateService.computeChangesSinceLastUpdate();
const transformedFrom = changes.mapPos(lastFrom);
const transformedTo = changes.mapPos(lastTo, 1);
return [transformedFrom, transformedTo];
}
}
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