Peggi : A Parsing framework for Parsing Expression Grammar
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Vim wiki
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| created by |
| Daniel Schemala |
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| script type |
| utility |
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| description |
Peggi is a parsing framework. On it's own, it's of not much use, but it can serve you when you write a Vim script that has to struggle with data too complicated to parse with regular expressions alone.
It's home is here: https://github.com/EinfachToll/peggi/
Basic Usage
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1. In your Vim script, first specify the formal grammar of your data as Parsing Expression Grammar (PEG)
2. Then start Peggi: `let result = peggi#peggi#parse(grammar, data, start-nonterminal)`
See the Readme for details.
Example
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As an example, let's look at a script that uses Peggi for processing arithmetic expressions:
let s:grammar = '
\ Expression = ( Term , /\s*[+-]/.strip() , Expression ).g:compute() | Term
\ Term = ( Factor , /\s*[*\/]/.strip() , Term ).g:compute() | Factor
\ Factor = ( /\s*(/ , Expression , /\s*)/ ).take("1") | /\s*[-0-9.]\+/.str2float()
\ '
function! g:compute(list)
if a:list[1] == '*'
return a:list[0] * a:list[2]
elseif a:list[1] == '/'
return a:list[0] / a:list[2]
elseif a:list[1] == '+'
return a:list[0] + a:list[2]
elseif a:list[1] == '-'
return a:list[0] - a:list[2]
endif
endfunction
let s:example = '-10 * (2* 2)/(0.6 +2)'
echo peggi#peggi#parse(s:grammar, s:example, 'Expression')
The output is -15.384615 |
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| install details |
| Use one of the many plugin managers for Vim, or install it manually by putting the folder `peggi/` into any `autoload/` directory in your runtimepath. |
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