123 lines
3.5 KiB
Markdown
123 lines
3.5 KiB
Markdown
---
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title: Tokenize a string with escaping
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id: 594faaab4e2a8626833e9c3d
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challengeType: 5
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---
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## Description
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<section id='description'>
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<p>
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Write a function or program that can split a string at each non-escaped occurrence of a separator character.
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</p>
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<p>
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It should accept three input parameters:
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</p>
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The <b>string</b>
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The <b>separator character</b>
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The <b>escape character</b>
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<p>It should output a list of strings.</p>
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<p>Rules for splitting:</p>
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The fields that were separated by the separators, become the elements of the output list.
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Empty fields should be preserved, even at the start and end.
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<p>Rules for escaping:</p>
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"Escaped" means preceded by an occurrence of the escape character that is not already escaped itself.
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When the escape character precedes a character that has no special meaning, it still counts as an escape (but does not do anything special).
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Each occurrences of the escape character that was used to escape something, should not become part of the output.
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<p>Demonstrate that your function satisfies the following test-case:
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Given string <pre>one^|uno||three^^^^|four^^^|^cuatro|</pre> and using
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<pre>|</pre> as a separator and <pre>^</pre> as escape character, your
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function should output the following array:
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</p>
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<pre>
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['one|uno', '', 'three^^', 'four^|quatro', '']
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</pre>
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>tokenize</code> is a function.
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testString: assert(typeof tokenize === 'function', '<code>tokenize</code> is a function.');
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- text: <code>tokenize</code> should return an array.
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testString: assert(typeof tokenize('a', 'b', 'c') === 'object', '<code>tokenize</code> should return an array.');
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- text: <code>tokenize('one^|uno||three^^^^|four^^^|^cuatro|', '|', '^') </code> should return <code>['one|uno', '', 'three^^', 'four^|cuatro', '']</code>
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testString: assert.deepEqual(tokenize(testStr1, '|', '^'), res1, "<code>tokenize('one^|uno||three^^^^|four^^^|^cuatro|', '|', '^') </code> should return ['one|uno', '', 'three^^', 'four^|cuatro', '']");
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- text: <code>tokenize('a@&bcd&ef&&@@hi', '&', '@')</code> should return <code>['a&bcd', 'ef', '', '@hi']</code>
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testString: assert.deepEqual(tokenize(testStr2, '&', '@'), res2, '<code>tokenize("a@&bcd&ef&&@@hi", "&", "@")</code> should return <code>["a&bcd", "ef", "", "@hi"]</code>');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function tokenize(str, esc, sep) {
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return true;
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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const testStr1 = 'one^|uno||three^^^^|four^^^|^cuatro|';
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const res1 = ['one|uno', '', 'three^^', 'four^|cuatro', ''];
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// TODO add more tests
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const testStr2 = 'a@&bcd&ef&&@@hi';
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const res2 = ['a&bcd', 'ef', '', '@hi'];
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// tokenize :: String -> Character -> Character -> [String]
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function tokenize(str, charDelim, charEsc) {
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const dctParse = str.split('')
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.reduce((a, x) => {
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const blnEsc = a.esc;
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const blnBreak = !blnEsc && x === charDelim;
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const blnEscChar = !blnEsc && x === charEsc;
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return {
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esc: blnEscChar,
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token: blnBreak ? '' : (
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a.token + (blnEscChar ? '' : x)
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),
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list: a.list.concat(blnBreak ? a.token : [])
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};
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}, {
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esc: false,
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token: '',
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list: []
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});
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return dctParse.list.concat(
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dctParse.token
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);
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}
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```
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</section>
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