Nearley is an open source grammar language created in 2014 by Kartik Chandra.
#221on PLDB | 10Years Old | 53Repos |
git clone https://github.com/Hardmath123/nearley
📜🔜🌲 Simple, fast, powerful parser toolkit for JavaScript.
# nearley grammar
@builtin "string.ne"
@{%
function insensitive(sl) {
var s = sl.literal;
result = [];
for (var i=0; i<s.length; i++) {
var c = s.charAt(i);
if (c.toUpperCase() !== c || c.toLowerCase() !== c) {
result.push(new RegExp("[" + c.toLowerCase() + c.toUpperCase() + "]"));
} else {
result.push({literal: c});
}
}
return {subexpression: [{tokens: result, postprocess: function(d) {return d.join(""); }}]};
}
%}
final -> whit? prog whit? {% function(d) { return d[1]; } %}
prog -> prod {% function(d) { return [d[0]]; } %}
| prod whit prog {% function(d) { return [d[0]].concat(d[2]); } %}
prod -> word whit? ("-"|"="):+ ">" whit? expression+ {% function(d) { return {name: d[0], rules: d[5]}; } %}
| word "[" wordlist "]" whit? ("-"|"="):+ ">" whit? expression+ {% function(d) {return {macro: d[0], args: d[2], exprs: d[8]}} %}
| "@" whit? js {% function(d) { return {body: d[2]}; } %}
| "@" word whit word {% function(d) { return {config: d[1], value: d[3]}; } %}
| "@include" whit? string {% function(d) {return {include: d[2].literal, builtin: false}} %}
| "@builtin" whit? string {% function(d) {return {include: d[2].literal, builtin: true }} %}
expression+ -> completeexpression
| expression+ whit? "|" whit? completeexpression {% function(d) { return d[0].concat([d[4]]); } %}
expressionlist -> completeexpression
| expressionlist whit? "," whit? completeexpression {% function(d) { return d[0].concat([d[4]]); } %}
wordlist -> word
| wordlist whit? "," whit? word {% function(d) { return d[0].concat([d[4]]); } %}
completeexpression -> expr {% function(d) { return {tokens: d[0]}; } %}
| expr whit? js {% function(d) { return {tokens: d[0], postprocess: d[2]}; } %}
expr_member ->
word {% id %}
| "TEMPLATEquot; word {% function(d) {return {mixin: d[1]}} %}
| word "[" expressionlist "]" {% function(d) {return {macrocall: d[0], args: d[2]}} %}
| string "i":? {% function(d) { if (d[1]) {return insensitive(d[0]); } else {return d[0]; } } %}
| "%" word {% function(d) {return {token: d[1]}} %}
| charclass {% id %}
| "(" whit? expression+ whit? ")" {% function(d) {return {'subexpression': d[2]} ;} %}
| expr_member whit? ebnf_modifier {% function(d) {return {'ebnf': d[0], 'modifier': d[2]}; } %}
ebnf_modifier -> ":+" {% id %} | ":*" {% id %} | ":?" {% id %}
expr -> expr_member
| expr whit expr_member {% function(d){ return d[0].concat([d[2]]); } %}
word -> [\w\?\+] {% function(d){ return d[0]; } %}
| word [\w\?\+] {% function(d){ return d[0]+d[1]; } %}
string -> dqstring {% function(d) {return { literal: d[0] }; } %}
#string -> "\"" charset "\"" {% function(d) { return { literal: d[1].join("") }; } %}
#
#charset -> null
# | charset char {% function(d) { return d[0].concat([d[1]]); } %}
#
#char -> [^\\"] {% function(d) { return d[0]; } %}
# | "\\" . {% function(d) { return JSON.parse("\""+"\\"+d[1]+"\""); } %}
charclass -> "." {% function(d) { return new RegExp("."); } %}
| "[" charclassmembers "]" {% function(d) { return new RegExp("[" + d[1].join('') + "]"); } %}
charclassmembers -> null
| charclassmembers charclassmember {% function(d) { return d[0].concat([d[1]]); } %}
charclassmember -> [^\\\]] {% function(d) { return d[0]; } %}
| "\\" . {% function(d) { return d[0] + d[1]; } %}
js -> "{" "%" jscode "%" "}" {% function(d) { return d[2]; } %}
jscode -> null {% function() {return "";} %}
| jscode [^%] {% function(d) {return d[0] + d[1];} %}
| jscode "%" [^}] {% function(d) {return d[0] + d[1] + d[2]; } %}
# Whitespace with a comment
whit -> whitraw
| whitraw? comment whit?
# Optional whitespace with a comment
whit? -> null
| whit
# Literally a string of whitespace
whitraw -> [\s]
| whitraw [\s]
# A string of whitespace OR the empty string
whitraw? -> null
| whitraw
comment -> "#" commentchars "\n"
commentchars -> null
| commentchars [^\n]
Feature | Supported | Example | Token |
---|---|---|---|
Booleans | ✓ | true false | |
Comments | ✓ | # A comment | |
Line Comments | ✓ | # A comment | # |
Semantic Indentation | X |