From aaa7386df6f2093edf853267a2b2ce633f96bd42 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:08:48 -0700
Subject: [PATCH 1/6] Setup files

---
 string_validator.rb      | 3 +++
 string_validator_test.rb | 8 ++++++++
 2 files changed, 11 insertions(+)
 create mode 100644 string_validator.rb
 create mode 100644 string_validator_test.rb

diff --git a/string_validator.rb b/string_validator.rb
new file mode 100644
index 0000000..153ef84
--- /dev/null
+++ b/string_validator.rb
@@ -0,0 +1,3 @@
+class StringValidator
+
+end
diff --git a/string_validator_test.rb b/string_validator_test.rb
new file mode 100644
index 0000000..09908c0
--- /dev/null
+++ b/string_validator_test.rb
@@ -0,0 +1,8 @@
+require 'minitest/autorun'
+require './string_validator'
+
+class StringValidatorTest < Minitest::Test
+  def test_it_exists
+    assert StringValidator
+  end
+end

From 24f51f6cd08905f0fccb4bdb849d8f424be83258 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:14:26 -0700
Subject: [PATCH 2/6] Validates empty string and single parens

---
 string_validator.rb      | 14 +++++++++++++-
 string_validator_test.rb | 16 ++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/string_validator.rb b/string_validator.rb
index 153ef84..0ec9229 100644
--- a/string_validator.rb
+++ b/string_validator.rb
@@ -1,3 +1,15 @@
 class StringValidator
-
+  def validate(target)
+    # consider just "()" and ")("
+    if target.length > 0
+      tokens = target.chars
+      if tokens[0] == "(" && tokens[1] == ")"
+        true
+      else
+        false
+      end
+    else
+      true
+    end
+  end
 end
diff --git a/string_validator_test.rb b/string_validator_test.rb
index 09908c0..b3f5cb7 100644
--- a/string_validator_test.rb
+++ b/string_validator_test.rb
@@ -5,4 +5,20 @@ class StringValidatorTest < Minitest::Test
   def test_it_exists
     assert StringValidator
   end
+
+  def test_an_empty_string_is_valid
+    sv = StringValidator.new
+    assert sv.validate("")
+  end
+
+  def test_single_parens_are_valid
+    sv = StringValidator.new
+    assert sv.validate("()")
+  end
+
+  def test_single_inverted_parens_are_not_valid
+    sv = StringValidator.new
+    refute sv.validate(")(")
+  end
+
 end

From 39deb7e405119bb71bd2013a6566f06011b0f878 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:19:48 -0700
Subject: [PATCH 3/6] Validate each kind of bracket

---
 string_validator.rb      | 10 +++++++++-
 string_validator_test.rb |  9 +++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/string_validator.rb b/string_validator.rb
index 0ec9229..89a3d58 100644
--- a/string_validator.rb
+++ b/string_validator.rb
@@ -1,9 +1,17 @@
 class StringValidator
+  def pairings
+    {
+      "(" => ")",
+      "[" => "]",
+      "{" => "}",
+    }
+  end
+
   def validate(target)
     # consider just "()" and ")("
     if target.length > 0
       tokens = target.chars
-      if tokens[0] == "(" && tokens[1] == ")"
+      if pairings[tokens[0]] == tokens[1]
         true
       else
         false
diff --git a/string_validator_test.rb b/string_validator_test.rb
index b3f5cb7..17bd9ad 100644
--- a/string_validator_test.rb
+++ b/string_validator_test.rb
@@ -21,4 +21,13 @@ def test_single_inverted_parens_are_not_valid
     refute sv.validate(")(")
   end
 
+  def test_single_square_brackets_are_valid
+    sv = StringValidator.new
+    assert sv.validate("[]")
+  end
+
+  def test_single_curly_brackets_are_valid
+    sv = StringValidator.new
+    assert sv.validate("{}")
+  end
 end

From 9f379d6cd248d235930ed0339bf0b62966ca4db4 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:22:02 -0700
Subject: [PATCH 4/6] Refactor how pairings are checked

---
 string_validator.rb | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/string_validator.rb b/string_validator.rb
index 89a3d58..fd68fef 100644
--- a/string_validator.rb
+++ b/string_validator.rb
@@ -7,17 +7,13 @@ def pairings
     }
   end
 
+  def matched_pair?(t1, t2)
+    pairings[t1] == t2
+  end
+
   def validate(target)
-    # consider just "()" and ")("
-    if target.length > 0
-      tokens = target.chars
-      if pairings[tokens[0]] == tokens[1]
-        true
-      else
-        false
-      end
-    else
-      true
-    end
+    true if target.empty?
+    tokens = target.chars
+    matched_pair?(tokens[0], tokens[1])
   end
 end

From ca9f4d7e5adbc7b4a2173934487229d80a111c87 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:46:35 -0700
Subject: [PATCH 5/6] Implemented stack-based multi-pair verification

---
 string_validator.rb      | 31 ++++++++++++++++++++++++++++---
 string_validator_test.rb | 31 +++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/string_validator.rb b/string_validator.rb
index fd68fef..992a144 100644
--- a/string_validator.rb
+++ b/string_validator.rb
@@ -1,4 +1,10 @@
 class StringValidator
+  attr_reader :token_stack
+
+  def initialize
+    @token_stack = []
+  end
+
   def pairings
     {
       "(" => ")",
@@ -11,9 +17,28 @@ def matched_pair?(t1, t2)
     pairings[t1] == t2
   end
 
+  def left?(token)
+    pairings.keys.include?(token)
+  end
+
+  def right?(token)
+    pairings.values.include?(token)
+  end
+
   def validate(target)
-    true if target.empty?
-    tokens = target.chars
-    matched_pair?(tokens[0], tokens[1])
+    answer = pairs_match?(target) && token_stack.empty?
+    token_stack.clear
+    return answer
+  end
+
+  def pairs_match?(input)
+    input.chars.all? do |token|
+      if left?(token)
+        token_stack.push(token)
+      elsif right?(token)
+        left = token_stack.pop
+        matched_pair?(left, token)
+      end
+    end
   end
 end
diff --git a/string_validator_test.rb b/string_validator_test.rb
index 17bd9ad..23f8933 100644
--- a/string_validator_test.rb
+++ b/string_validator_test.rb
@@ -30,4 +30,35 @@ def test_single_curly_brackets_are_valid
     sv = StringValidator.new
     assert sv.validate("{}")
   end
+
+  def test_two_pairs_of_matched_brackets_are_valid
+    sv = StringValidator.new
+    assert sv.validate("{}()")
+  end
+
+  def test_mismatched_second_brackets_are_invalid
+    sv = StringValidator.new
+    refute sv.validate("{})(")
+  end
+
+  def test_complex_nesting_is_valid
+    sv = StringValidator.new
+    assert sv.validate("([{}[]])")
+  end
+
+  def test_complex_nesting_with_some_trash_is_invalid
+    sv = StringValidator.new
+    refute sv.validate("([{}[]])]")
+  end
+
+  def test_complex_nesting_with_some_other_trash_is_invalid
+    sv = StringValidator.new
+    refute sv.validate("([{}[]])[")
+  end
+
+  def test_validating_a_second_input_works_correctly
+    sv = StringValidator.new
+    refute sv.validate("([{}[]])[")
+    assert sv.validate("()")
+  end
 end

From 452b6cfe702625f127e301afc96233801bb3f296 Mon Sep 17 00:00:00 2001
From: Jeff Casimir <jeff@casimircreative.com>
Date: Fri, 3 Feb 2017 11:50:37 -0700
Subject: [PATCH 6/6] Renaming variable to have another commit

---
 string_validator.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/string_validator.rb b/string_validator.rb
index 992a144..f6b5d04 100644
--- a/string_validator.rb
+++ b/string_validator.rb
@@ -31,8 +31,8 @@ def validate(target)
     return answer
   end
 
-  def pairs_match?(input)
-    input.chars.all? do |token|
+  def pairs_match?(target)
+    target.chars.all? do |token|
       if left?(token)
         token_stack.push(token)
       elsif right?(token)