From d3132a5463908bcabd0578ad48a457b2bec30a9a Mon Sep 17 00:00:00 2001 From: Marcin Chrzanowski Date: Fri, 14 Jul 2017 18:14:14 -0400 Subject: Lex and parse subtraction --- src/lexer.js | 1 + src/parser.js | 8 ++++++++ 2 files changed, 9 insertions(+) (limited to 'src') diff --git a/src/lexer.js b/src/lexer.js index 97130d8..fd347c6 100644 --- a/src/lexer.js +++ b/src/lexer.js @@ -21,6 +21,7 @@ const newSkippableLexeme = (type, regex) => { newValueLexeme('constant', '\\d+', Number) newLexemeType('d', 'd') newLexemeType('+', '\\+') +newLexemeType('-', '-') newSkippableLexeme('whitespace', '\\s+') const lex = (expressionString) => { diff --git a/src/parser.js b/src/parser.js index c7d91c3..6c39c77 100644 --- a/src/parser.js +++ b/src/parser.js @@ -32,6 +32,14 @@ newSymbol('+', null, 20, (left, parser) => { } }) +newSymbol('-', null, 20, (left, parser) => { + return { + type: 'subtract', + left: left, + right: parser.expression(20) + } +}) + newSymbol('end', null, -1) const newParser = (tokens) => { -- cgit v1.2.3