From 467660e024bad8e2e084aa703686d0856a7e88b9 Mon Sep 17 00:00:00 2001
From: Matthew Hall <hallmatthew314@gmail.com>
Date: Sat, 18 Mar 2023 21:44:26 +1300
Subject: Sequence, +, and variants

---
 spec/parcom_spec.cr | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

(limited to 'spec')

diff --git a/spec/parcom_spec.cr b/spec/parcom_spec.cr
index 6acd1b2..86ad93a 100644
--- a/spec/parcom_spec.cr
+++ b/spec/parcom_spec.cr
@@ -170,6 +170,52 @@ describe Parser do
     end
   end
 
+  describe "self.sequence" do
+    it "always succeeds with 0 parsers" do
+      p = Parser(Char, Char).sequence([] of Parser(Char, Char))
+      tokens = Tokens.from_string("")
+      result = p.parse(tokens)
+
+      result.value.empty?.should be_true
+      result.tokens.should eq(tokens)
+    end
+
+    p = Parser(Char, Char).sequence([
+      Parser(Char, Char).token('a'),
+      Parser(Char, Char).token('b'),
+      Parser(Char, Char).token('c'),
+    ])
+
+    it "runs each parser in sequence" do
+      tokens = Tokens.from_string("abcd")
+      result = p.parse(tokens)
+
+      result.value.should eq("abc".chars)
+      result.tokens.should eq(tokens[3..])
+    end
+
+    it "fails if any of the parsers fail" do
+      "xbc axc abx".split.each do |s|
+        tokens = Tokens.from_string(s)
+        expect_raises(ParserFail) { p.parse(tokens) }
+      end
+    end
+  end
+
+  # most testing should be able to be skipped, since it is already
+  # done for `Parser.sequence`
+  describe "self.token_sequence" do
+    p = Parser(Char, Char).token_sequence("abc".chars)
+
+    it "parses the specified tokens in sequence" do
+      tokens = Tokens.from_string("abcd")
+      result = p.parse(tokens)
+
+      result.value.should eq("abc".chars)
+      result.tokens.should eq(tokens[3..])
+    end
+  end
+
   describe "#assert" do
     p = Parser(Char, Char).any_token.assert { |c| c == 'a' }
 
@@ -284,7 +330,55 @@ describe Parser do
     it "does not modify the input when recovering" do
       result2.tokens.should eq(tokens2)
     end
+  end
+
+  describe "#+" do
+    a = Parser(Char, Char).token('a')
+    b = Parser(Char, Char).token('b')
+    p = a + b
+
+    it "combines both success results if both parsers succeed" do
+      tokens = Tokens.from_string("abcd")
+      result = p.parse(tokens)
+
+      result.value.should eq({'a', 'b'})
+      result.tokens.should eq(tokens[2..])
+    end
+
+    it "fails if either parser fails" do
+      "aacd bbcd cccd".split.each do |s|
+        tokens = Tokens.from_string(s)
+        expect_raises(ParserFail) { p.parse(tokens) }
+      end
+    end
+  end
+
+  # Should be able to skip some tests because they are already
+  # written for #+, which this is based on.
+  describe "#<<" do
+    a = Parser(Char, Char).token('a')
+    b = Parser(Char, Char).token('b')
+    p = a << b
+    tokens = Tokens.from_string("abcd")
+    result = p.parse(tokens)
+
+    it "discards the second parser's value" do
+      result.value.should eq('a')
+    end
+  end
 
+  # Should be able to skip some tests because they are already
+  # written for #+, which this is based on.
+  describe "#>>" do
+    a = Parser(Char, Char).token('a')
+    b = Parser(Char, Char).token('b')
+    p = a >> b
+    tokens = Tokens.from_string("abcd")
+    result = p.parse(tokens)
+
+    it "discards the second parser's value" do
+      result.value.should eq('b')
+    end
   end
 end
 
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