Added optional Lua lexer support.

This support is disabled by default and must be enabled via compile-time option.

1 files changed, 45 insertions, 0 deletions

diff --git a/lexlua/haskell.lua b/lexlua/haskell.lua
new file mode 100644
index 000000000..484069cb3
--- /dev/null
+++ b/lexlua/haskell.lua
@@ -0,0 +1,45 @@
+-- Copyright 2006-2018 Mitchell mitchell.att.foicica.com. See License.txt.
+-- Haskell LPeg lexer.
+-- Modified by Alex Suraci.
+
+local lexer = require('lexer')
+local token, word_match = lexer.token, lexer.word_match
+local P, R, S = lpeg.P, lpeg.R, lpeg.S
+
+local lex = lexer.new('haskell', {fold_by_indentation = true})
+
+-- Whitespace.
+lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
+
+-- Keywords.
+lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
+  case class data default deriving do else if import in infix infixl infixr
+  instance let module newtype of then type where _ as qualified hiding
+]]))
+
+local word = (lexer.alnum + S("._'#"))^0
+local op = lexer.punct - S('()[]{}')
+
+-- Types & type constructors.
+lex:add_rule('type', token(lexer.TYPE, (lexer.upper * word) +
+                                       (":" * (op^1 - ":"))))
+
+-- Identifiers.
+lex:add_rule('identifier', token(lexer.IDENTIFIER, (lexer.alpha + '_') * word))
+
+-- Strings.
+lex:add_rule('string', token(lexer.STRING, lexer.delimited_range("'", true) +
+                                           lexer.delimited_range('"')))
+
+-- Comments.
+local line_comment = '--' * lexer.nonnewline_esc^0
+local block_comment = '{-' * (lexer.any - '-}')^0 * P('-}')^-1
+lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))
+
+-- Numbers.
+lex:add_rule('number', token(lexer.NUMBER, lexer.float + lexer.integer))
+
+-- Operators.
+lex:add_rule('operator', token(lexer.OPERATOR, op))
+
+return lex