From 60be5fc8a6be8f60ed37af30ef18f02639259774 Mon Sep 17 00:00:00 2001 From: Matthew Hall Date: Sat, 11 Mar 2023 00:02:12 +1300 Subject: Implement FirstOf --- spec/parcom_spec.cr | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) (limited to 'spec/parcom_spec.cr') diff --git a/spec/parcom_spec.cr b/spec/parcom_spec.cr index fd4b470..77a14dd 100644 --- a/spec/parcom_spec.cr +++ b/spec/parcom_spec.cr @@ -614,7 +614,38 @@ end pending StopIf do end -pending FirstOf do +describe FirstOf do + tokens = TokenStream.from_string("abcd") + letter_a = Token.new('a') + f = Flunk(Char, Char).new + + describe "#parse" do + it "cannot be instantiated with an empty Enumerable" do + expect_raises(ArgumentError) { FirstOf.new([] of Parser(Char, Char)) } + end + + it "uses the result of the first successful parser" do + a1 = [letter_a, f, f, f] of Parser(Char, Char) + a2 = [f, letter_a, f, f] of Parser(Char, Char) + a3 = [f, f, letter_a, f] of Parser(Char, Char) + a4 = [f, f, f, letter_a] of Parser(Char, Char) + + [a1, a2, a3, a4].each do |arr| + p = FirstOf.new(arr) + r = p.parse(tokens) + r.value.should eq('a') + r.tokens.should eq(tokens[1..]) + end + end + + it "only fails if no parsers are successful" do + x = Token.new('x') + y = Token.new('x') + z = Token.new('x') + p = FirstOf.new([x, y, z] of Parser(Char, Char)) + expect_raises(ParserException) { p.parse(tokens) } + end + end end pending SepBy do -- cgit v1.2.1