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| -- Copyright 2013-2018 Michael T. Richter. See License.txt.
| -- SNOBOL4 lexer.
| -- This lexer works with classic SNOBOL4 as well as the CSNOBOL4 extensions.
|
| local lexer = require 'lexer'
| local token, word_match = lexer.token, lexer.word_match
| local B, P, R, S, V = lpeg.B, lpeg.P, lpeg.R, lpeg.S, lpeg.V
|
| local M = { _NAME = 'snobol4' }
|
| -- Helper patterns.
| local dotted_id = lexer.word * (P'.' * lexer.word)^0
|
| local dq_str = lexer.delimited_range('"', true, true)
| local sq_str = lexer.delimited_range("'", true, true)
|
| local branch = B(lexer.space * P':(') * dotted_id * #P')'
| local sbranch = B(lexer.space * P':' * S'SF' * '(') * dotted_id * #P')'
| local sbranchx = B(P')' * S'SF' * P'(') * dotted_id * #P')'
|
| -- Token definitions.
| local bif = token(lexer.FUNCTION, word_match({
| 'APPLY', 'ARRAY', 'CHAR', 'CONVERT', 'COPY', 'DATA', 'DATE', 'DIFFER', 'DUPL',
| 'EQ', 'EVAL', 'FILE_ABSPATH', 'FILE_ISDIR', 'FREEZE', 'FUNCTION', 'GE', 'GT',
| 'HOST', 'IDENT', 'INTEGER', 'IO_FINDUNIT', 'ITEM', 'LABEL', 'LOAD', 'LPAD',
| 'LE', 'LGT', 'LT', 'NE', 'OPSYN', 'ORD', 'PROTOTYPE', 'REMDR', 'REPLACE',
| 'REVERSE', 'RPAD', 'RSORT', 'SERV_LISTEN', 'SET', 'SETEXIT', 'SIZE', 'SORT',
| 'SQRT', 'SSET', 'SUBSTR', 'TABLE', 'THAW', 'TIME', 'TRACE', 'TRIM', 'UNLOAD',
| 'VALUE', 'VDIFFER',
| }, '', true) * #lexer.delimited_range('()', false, true, true))
| local comment = token(lexer.COMMENT,
| lexer.starts_line(S'*#|;!' * lexer.nonnewline^0))
| local control = token(lexer.PREPROCESSOR, lexer.starts_line(P'-' * lexer.word))
| local identifier = token(lexer.DEFAULT, dotted_id)
| local keyword = token(lexer.KEYWORD, word_match({
| 'ABORT', 'ARRAY', 'CONTINUE', 'DEFINE', 'END', 'FRETURN', 'INPUT', 'NRETURN',
| 'OUTPUT', 'PUNCH', 'RETURN', 'SCONTINUE', 'TABLE',
| }, '', true) + P'&' * lexer.word)
| local label = token(lexer.LABEL, lexer.starts_line(dotted_id))
| local number = token(lexer.NUMBER, lexer.float + lexer.integer)
| local operator = token(lexer.OPERATOR, S'¬?$.!%*/#+-@⊥&^~\\=')
| local pattern = lexer.token(lexer.CLASS, word_match({ -- keep distinct
| 'ABORT', 'ANY', 'ARB', 'ARBNO', 'BAL', 'BREAK', 'BREAKX', 'FAIL', 'FENCE',
| 'LEN', 'NOTANY', 'POS', 'REM', 'RPOS', 'RTAB', 'SPAN', 'SUCCEED', 'TAB',
| }, '', true) * #lexer.delimited_range('()', false, true, true))
| local str = token(lexer.STRING, sq_str + dq_str)
| local target = token(lexer.LABEL, branch + sbranch + sbranchx)
| local ws = token(lexer.WHITESPACE, lexer.space^1)
|
| M._rules = {
| { 'comment', comment },
| { 'control', control },
| { 'string', str },
| { 'number', number },
| { 'keyword', keyword },
| { 'label', label },
| { 'target', target },
| { 'pattern', pattern },
| { 'built-in', bif },
| { 'operator', operator },
| { 'identifier', identifier },
| { 'whitespace', ws },
| }
|
| return M
|
|
