lex newline

spec/zodiac/lexer_spec.rb

@@ -29,6 +29,15 @@
     end
 
     context 'when happy path' do
+      it 'lexs newlines' do
+        input = "\n"
+        lexer = described_class.new(input)
+
+        expected_output = [{ kind: 'NEWLINE', value: "\n" }]
+
+        expect(lexer.lex).to eq(expected_output)
+      end
+
       it 'lexs symbols' do
         input = ':[ ]{}@~$!?:='
         lexer = described_class.new(input)
@@ -178,8 +187,11 @@
 
         expected_output = [
           { kind: 'COMMENT', value: '# this is a comment' },
+          { kind: 'NEWLINE', value: "\n" },
           { kind: 'COMMENT', value: '# this is another comment' },
-          { kind: 'COMMENT', value: '# this is a third comment' }
+          { kind: 'NEWLINE', value: "\n" },
+          { kind: 'COMMENT', value: '# this is a third comment' },
+          { kind: 'NEWLINE', value: "\n" }
         ]
 
         expect(lexer.lex).to eq(expected_output)

spec/zodiac/parser_spec.rb

@@ -10,7 +10,7 @@
         parser = described_class.new('')
 
         actual = parser.parse
-        expected = { kind: 'PROGRAM', value: [] }
+        expected = { kind: 'PROGRAM', cmp_stmts: [] }
 
         expect(actual).to eq(expected)
       end

src/zodiac/lexer.rb

@@ -21,7 +21,7 @@ class Lexer
     def initialize(raw_string)
       @input_iterator = StringCharacterIterator.new(raw_string)
       @lexer_evaluator_engine = LexerEvaluatorEngine.new(
-        [comment_lexer, op_assign_lexer, symbol_lexer, identifier_lexer, string_lexer, number_lexer],
+        [comment_lexer, newline_lexer, op_assign_lexer, symbol_lexer, identifier_lexer, string_lexer, number_lexer],
         proc { @input_iterator.iterate }
       )
     end
@@ -37,7 +37,6 @@ def lex
     private
 
     ### Comment lexing ###
-
     def comment_lexer
       LexerEvaluator.new('COMMENT', method(:comment?), method(:lex_comment))
     end
@@ -46,6 +45,19 @@ def lex_comment
       @input_iterator.take_until(proc { |val| val == "\n" })
     end
 
+    ### Newline lexing ###
+    def newline_lexer
+      LexerEvaluator.new('NEWLINE', method(:newline?), method(:lex_newline))
+    end
+
+    def lex_newline
+      @input_iterator.iterate
+    end
+
+    def newline?(_value)
+      @input_iterator.peek == "\n"
+    end
+
     ### Operator Assignment lexing ###
     def lex_op_assign
       @input_iterator.take_until(proc { |val| val == '=' }, after: 1)

src/zodiac/parse_error.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+module Zodiac
+  class ParseError < StandardError
+  end
+end

src/zodiac/parser.rb

@@ -173,7 +173,7 @@ def parse_program
 
       cmp_stmts << parse_compstmt while @cur_index < @tokens.length
 
-      { kind: 'PROGRAM', value: cmp_stmts }
+      { kind: 'PROGRAM', cmp_stmts: }
     end
 
     # COMPSTMT	: STMT (TERM EXPR)* [TERM]
@@ -212,7 +212,14 @@ def parse_expr
     # TERM		: `;'
     # 		| `\n'
     def parse_term
-      { kind: 'TERM', value: nil }
+      cur_token = @tokens[@cur_index]
+
+      unless cur_token[:kind] == 'NEWLINE' || (cur_token[:kind] == 'SYMBOL' && cur_token[:value] == ';')
+        raise ParseError,
+              "Expected a newline or a semicolon. Received #{cur_token[:value]}"
+      end
+
+      { kind: 'TERM', value: cur_token[:value] }
     end
 
     # CALL		: FUNCTION