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Overview

The containsSource function checks if an exact source string exists in the trie produced by buildTrie. This is useful to verify if a source word has been included in the trie and is therefore searchable and replaceable using the searchAndReplace function.

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Function signature

containsSource(trie: TrieNode, text: string): boolean

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Parameters

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trie
TrieNode
required
The trie to search within. This trie should be constructed using the buildTrie function.
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text
string
required
The candidate source string to look up. The function checks if this exact string exists as a source in the trie.

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Returns

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result
boolean
True if the trie contains the source string, otherwise false. The function returns true only if the string exists as a complete source word with an associated target.

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Example usage

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Basic usage

import { buildTrie, containsSource } from 'trie-rules';

const rules = [
  {
    from: ['example', 'sample'],
    to: 'demo',
  },
  {
    from: ['test'],
    to: 'verified',
  },
];

const trie = buildTrie(rules);

// Check if sources exist in the trie
console.log(containsSource(trie, 'example'));
// Output: true

console.log(containsSource(trie, 'sample'));
// Output: true

console.log(containsSource(trie, 'test'));
// Output: true

console.log(containsSource(trie, 'notfound'));
// Output: false

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Checking partial matches

import { buildTrie, containsSource } from 'trie-rules';

const rules = [
  {
    from: ['testing'],
    to: 'verified',
  },
];

const trie = buildTrie(rules);

// Only exact matches return true
console.log(containsSource(trie, 'testing'));
// Output: true

console.log(containsSource(trie, 'test'));
// Output: false (partial match, not a complete source)

console.log(containsSource(trie, 'testings'));
// Output: false (longer than the source)

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Verifying rule coverage

import { buildTrie, containsSource } from 'trie-rules';

const rules = [
  {
    from: ['Sufyan', 'Ali', 'Umar'],
    to: 'Companion',
  },
];

const trie = buildTrie(rules);

// Verify all sources were added
const sources = ['Sufyan', 'Ali', 'Umar'];
const allPresent = sources.every(source => containsSource(trie, source));

console.log(allPresent);
// Output: true

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Implementation details

The function performs a character-by-character traversal of the trie:
  1. Starting at the root node, iterate through each character of the input text
  2. For each character, check if a corresponding child node exists
  3. If any character is not found, return false immediately
  4. After traversing all characters, check if the final node has a target (indicating a complete source word)
  5. Return true only if a target exists at the final node

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Runtime complexity

The complexity is O(k) where:
  • k = length of the text string to look up
The function performs a single linear traversal through the trie based on the characters in the input string.

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Use cases

  • Validation: Verify that expected sources were added to the trie after building
  • Testing: Confirm rule coverage in unit tests
  • Debugging: Check if a specific source is present when troubleshooting replacement issues
  • Rule management: Determine if a source already exists before adding new rules

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