178 lines
6.3 KiB
Markdown
178 lines
6.3 KiB
Markdown
# character-parser
|
|
|
|
Parse JavaScript one character at a time to look for snippets in Templates. This is not a validator, it's just designed to allow you to have sections of JavaScript delimited by brackets robustly.
|
|
|
|
[](https://travis-ci.org/ForbesLindesay/character-parser)
|
|
|
|
## Installation
|
|
|
|
npm install character-parser
|
|
|
|
## Usage
|
|
|
|
### Parsing
|
|
|
|
Work out how much depth changes:
|
|
|
|
```js
|
|
var state = parse('foo(arg1, arg2, {\n foo: [a, b\n');
|
|
assert.deepEqual(state.stack, [')', '}', ']']);
|
|
|
|
parse(' c, d]\n })', state);
|
|
assert.deepEqual(state.stack, []);
|
|
```
|
|
|
|
### Custom Delimited Expressions
|
|
|
|
Find code up to a custom delimiter:
|
|
|
|
```js
|
|
// EJS-style
|
|
var section = parser.parseUntil('foo.bar("%>").baz%> bing bong', '%>');
|
|
assert(section.start === 0);
|
|
assert(section.end === 17); // exclusive end of string
|
|
assert(section.src = 'foo.bar("%>").baz');
|
|
|
|
var section = parser.parseUntil('<%foo.bar("%>").baz%> bing bong', '%>', {start: 2});
|
|
assert(section.start === 2);
|
|
assert(section.end === 19); // exclusive end of string
|
|
assert(section.src = 'foo.bar("%>").baz');
|
|
|
|
// Jade-style
|
|
var section = parser.parseUntil('#[p= [1, 2][i]]', ']', {start: 2})
|
|
assert(section.start === 2);
|
|
assert(section.end === 14); // exclusive end of string
|
|
assert(section.src === 'p= [1, 2][i]')
|
|
|
|
// Dumb parsing
|
|
// Stop at first delimiter encountered, doesn't matter if it's nested or not
|
|
// This is the character-parser@1 default behavior.
|
|
var section = parser.parseUntil('#[p= [1, 2][i]]', '}', {start: 2, ignoreNesting: true})
|
|
assert(section.start === 2);
|
|
assert(section.end === 10); // exclusive end of string
|
|
assert(section.src === 'p= [1, 2')
|
|
''
|
|
```
|
|
|
|
Delimiters are ignored if they are inside strings or comments.
|
|
|
|
## API
|
|
|
|
All methods may throw an exception in the case of syntax errors. The exception contains an additional `code` property that always starts with `CHARACTER_PARSER:` that is unique for the error.
|
|
|
|
### parse(str, state = defaultState(), options = {start: 0, end: src.length})
|
|
|
|
Parse a string starting at the index start, and return the state after parsing that string.
|
|
|
|
If you want to parse one string in multiple sections you should keep passing the resulting state to the next parse operation.
|
|
|
|
Returns a `State` object.
|
|
|
|
### parseUntil(src, delimiter, options = {start: 0, ignoreLineComment: false, ignoreNesting: false})
|
|
|
|
Parses the source until the first occurence of `delimiter` which is not in a string or a comment.
|
|
|
|
If `ignoreLineComment` is `true`, it will still count if the delimiter occurs in a line comment.
|
|
|
|
If `ignoreNesting` is `true`, it will stop at the first bracket, not taking into account if the bracket part of nesting or not. See example above.
|
|
|
|
It returns an object with the structure:
|
|
|
|
```js
|
|
{
|
|
start: 0,//index of first character of string
|
|
end: 13,//index of first character after the end of string
|
|
src: 'source string'
|
|
}
|
|
```
|
|
|
|
### parseChar(character, state = defaultState())
|
|
|
|
Parses the single character and returns the state. See `parse` for the structure of the returned state object. N.B. character must be a single character not a multi character string.
|
|
|
|
### defaultState()
|
|
|
|
Get a default starting state.
|
|
|
|
### isPunctuator(character)
|
|
|
|
Returns `true` if `character` represents punctuation in JavaScript.
|
|
|
|
### isKeyword(name)
|
|
|
|
Returns `true` if `name` is a keyword in JavaScript.
|
|
|
|
### TOKEN_TYPES & BRACKETS
|
|
|
|
Objects whose values can be a frame in the `stack` property of a State (documented below).
|
|
|
|
## State
|
|
|
|
A state is an object with the following structure
|
|
|
|
```js
|
|
{
|
|
stack: [], // stack of detected brackets; the outermost is [0]
|
|
regexpStart: false, // true if a slash is just encountered and a REGEXP state has just been added to the stack
|
|
|
|
escaped: false, // true if in a string and the last character was an escape character
|
|
hasDollar: false, // true if in a template string and the last character was a dollar sign
|
|
|
|
src: '', // the concatenated source string
|
|
history: '', // reversed `src`
|
|
lastChar: '' // last parsed character
|
|
}
|
|
```
|
|
|
|
`stack` property can contain any of the following:
|
|
|
|
- Any of the property values of `characterParser.TOKEN_TYPES`
|
|
- Any of the property values of `characterParser.BRACKETS` (the end bracket, not the starting bracket)
|
|
|
|
It also has the following useful methods:
|
|
|
|
- `.current()` returns the innermost bracket (i.e. the last stack frame).
|
|
- `.isString()` returns `true` if the current location is inside a string.
|
|
- `.isComment()` returns `true` if the current location is inside a comment.
|
|
- `.isNesting([opts])` returns `true` if the current location is not at the top level, i.e. if the stack is not empty. If `opts.ignoreLineComment` is `true`, line comments are not counted as a level, so for `// a` it will still return false.
|
|
|
|
### Errors
|
|
|
|
All errors thrown by character-parser has a `code` property attached to it that allows one to identify what sort of error is thrown. For errors thrown from `parse` and `parseUntil`, an additional `index` property is available.
|
|
|
|
## Transition from v1
|
|
|
|
In character-parser@2, we have changed the APIs quite a bit. These are some notes that will help you transition to the new version.
|
|
|
|
### State Object Changes
|
|
|
|
Instead of keeping depths of different brackets, we are now keeping a stack. We also removed some properties:
|
|
|
|
```js
|
|
state.lineComment → state.current() === parser.TOKEN_TYPES.LINE_COMMENT
|
|
state.blockComment → state.current() === parser.TOKEN_TYPES.BLOCK_COMMENT
|
|
state.singleQuote → state.current() === parser.TOKEN_TYPES.SINGLE_QUOTE
|
|
state.doubleQuote → state.current() === parser.TOKEN_TYPES.DOUBLE_QUOTE
|
|
state.regexp → state.current() === parser.TOKEN_TYPES.REGEXP
|
|
```
|
|
|
|
### `parseMax`
|
|
|
|
This function has been removed since the usefulness of this function has been questioned. You should find that `parseUntil` is a better choice for your task.
|
|
|
|
### `parseUntil`
|
|
|
|
The default behavior when the delimiter is a bracket has been changed so that nesting is taken into account to determine if the end is reached.
|
|
|
|
To preserve the original behavior, pass `ignoreNesting: true` as an option.
|
|
|
|
To see the difference between the new and old behaviors, see the "Usage" section earlier.
|
|
|
|
### `parseMaxBracket`
|
|
|
|
This function has been merged into `parseUntil`. You can directly rename the function call without any repercussions.
|
|
|
|
## License
|
|
|
|
MIT
|