Tianyi Cui
101 lines
3.7 KiB
TypeScript
101 lines
3.7 KiB
TypeScript
/** JSON string-prefix accounting for the outer-output ledger. @module @deepseek-ai/dsh-code-runtime-worker/output-json */
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import type { CodeJsonValue } from '@deepseek-ai/dsh-code-runtime'
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/** Control characters with a two-byte short JSON escape instead of `\u00XX`. */
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const SHORT_ESCAPE_CODES = new Set([0x08, 0x09, 0x0a, 0x0c, 0x0d])
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/** Serialized bytes contributed by one complete Unicode code point inside JSON quotes. */
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function serializedCharacterBytes(character: string): number {
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if (character.length === 2) return 4
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if (character === '"' || character === '\\') return 2
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const code = character.charCodeAt(0)
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if (code >= 0xd800 && code <= 0xdfff) return 6
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if (code < 0x20) return SHORT_ESCAPE_CODES.has(code) ? 2 : 6
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return Buffer.byteLength(character, 'utf8')
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}
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/**
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* Measure one JSON string without materializing its complete escaped form.
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* @param text - the candidate string.
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* @param maxBytes - largest serialized size the caller can admit.
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* @returns Exact serialized bytes, or `undefined` as soon as the cap is crossed.
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*/
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export function jsonStringBytesUpTo(text: string, maxBytes: number): number | undefined {
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if (maxBytes < 2) return undefined
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let bytes = 2
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for (const character of text) {
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bytes += serializedCharacterBytes(character)
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if (bytes > maxBytes) return undefined
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}
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return bytes
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}
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/**
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* Measure one lossless JSON value without allocating its serialized form.
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* @param value - already validated lossless JSON.
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* @param maxBytes - largest serialized size the caller can admit.
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* @returns Exact serialized bytes, or `undefined` as soon as the cap is crossed.
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*/
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export function jsonValueBytesUpTo(value: CodeJsonValue, maxBytes: number): number | undefined {
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if (value === null) return maxBytes >= 4 ? 4 : undefined
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if (typeof value === 'string') return jsonStringBytesUpTo(value, maxBytes)
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if (typeof value === 'number') {
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const bytes = Buffer.byteLength(String(value), 'utf8')
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return bytes <= maxBytes ? bytes : undefined
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}
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if (typeof value === 'boolean') {
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const bytes = value ? 4 : 5
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return bytes <= maxBytes ? bytes : undefined
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}
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let bytes = 2
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if (bytes > maxBytes) return undefined
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if (Array.isArray(value)) {
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for (let index = 0; index < value.length; index++) {
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if (index > 0 && ++bytes > maxBytes) return undefined
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const item = value[index]
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if (item === undefined) return undefined
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const itemBytes = jsonValueBytesUpTo(item, maxBytes - bytes)
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if (itemBytes === undefined) return undefined
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bytes += itemBytes
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}
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return bytes
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}
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let entries = 0
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for (const [key, item] of Object.entries(value)) {
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if (entries > 0 && ++bytes > maxBytes) return undefined
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const keyBytes = jsonStringBytesUpTo(key, maxBytes - bytes)
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if (keyBytes === undefined) return undefined
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bytes += keyBytes + 1
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if (bytes > maxBytes) return undefined
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const itemBytes = jsonValueBytesUpTo(item, maxBytes - bytes)
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if (itemBytes === undefined) return undefined
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bytes += itemBytes
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entries += 1
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}
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return bytes
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}
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/**
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* Return the longest code-point-aligned prefix whose JSON string encoding,
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* including its surrounding quotes, fits `maxBytes`.
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*
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* @param text - the candidate string.
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* @param maxBytes - serialized JSON-string bytes available.
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* @returns the fitting prefix, or an empty string when even useful content cannot fit.
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*/
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export function truncateJsonStringBytes(text: string, maxBytes: number): string {
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if (maxBytes < 2) return ''
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let bytes = 2
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let end = 0
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for (const character of text) {
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const cost = serializedCharacterBytes(character)
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if (bytes + cost > maxBytes) break
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bytes += cost
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end += character.length
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}
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return end === text.length ? text : text.slice(0, end)
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}
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