matchRule

CORE · function · Runtime value

Dispatch to the first matching rule.

A rule without a pattern matches unconditionally, so the table's order decides precedence. The first match owns the result even when its handler returns undefined, and later rules are not consulted.

Import

TypeScript

import { matchRule } from '@jangts/agent-core/support';

JavaScript

import { matchRule } from '@jangts/agent-core/support';

Other public entry points:@jangts/agent-core, @jangts/agent-core/types, @jangts/agent-core/support.

Definition

Type parameters

Type parameter	Constraint	Default type
Input	—	—
Result	—	—

Call

matchRule<Input, Result>(rules: readonly MatchRule<Input, Result>[], input: Input): Result | undefined

Dispatch to the first matching rule.

A rule without a pattern matches unconditionally, so the table's order decides precedence. The first match owns the result even when its handler returns undefined, and later rules are not consulted.

Type parameter	Constraint	Default type
Input	—	—
Result	—	—

Parameter	Type	Passing	Description
rules	readonly MatchRule<Input, Result>[]	Required	—
input	Input	Required	—

Returns: Result \| undefined.

Awaited value: Awaited<Result> \| undefined.

Examples

• Rejection checks, first match, and sequential processing: Use real lists to express multiple checks and enumerated dispatch; a single ordinary condition can still use if.

One explicit rejection

Beginner · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const input = '你好';
Support.breakWhile(!input.trim(), '问题不能为空');
console.log(input);

JavaScript

import { Support } from '@jangts/agent-core';
const input = '你好';
Support.breakWhile(!input.trim(), '问题不能为空');
console.log(input);

Checks with dependencies evaluated in order

Configuration · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const input: unknown = { name: 'Ivan' };
Support.breakWhile([
  { occur: !input || typeof input !== 'object', error: '需要对象' },
  { occur: () => !('name' in (input as object)), error: '缺少 name' },
]);
console.log(input);

JavaScript

import { Support } from '@jangts/agent-core';
const input = { name: 'Ivan' };
Support.breakWhile([
    { occur: !input || typeof input !== 'object', error: '需要对象' },
    { occur: () => !('name' in input), error: '缺少 name' },
]);
console.log(input);

Declarative priority dispatch and sequential transformation

Extension · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const routeName = Support.matchRule([
  { id: 'status', description: '状态意图', pattern: (input: string) => input === 'status', handle: () => 'service' },
  { id: 'fallback', description: '其他意图', handle: () => 'reply' },
], 'status');
const state = { answer: '  服务正常  ' };
Support.walkRules([
  { handle: (value: typeof state) => { value.answer = value.answer.trim(); } },
  { pattern: (value: typeof state) => !!value.answer, handle: value => { value.answer += '。'; } },
], state);
console.log(routeName, state.answer);

JavaScript

import { Support } from '@jangts/agent-core';
const routeName = Support.matchRule([
    { id: 'status', description: '状态意图', pattern: (input) => input === 'status', handle: () => 'service' },
    { id: 'fallback', description: '其他意图', handle: () => 'reply' },
], 'status');
const state = { answer: '  服务正常  ' };
Support.walkRules([
    { handle: (value) => { value.answer = value.answer.trim(); } },
    { pattern: (value) => !!value.answer, handle: value => { value.answer += '。'; } },
], state);
console.log(routeName, state.answer);

Related policy source

• Actual rules for rejection checks and match short-circuiting

Related definitions

• MatchRule