Add matching-brackets (#255)

config.json

@@ -437,6 +437,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "matching-brackets",
+        "name": "Matching Brackets",
+        "uuid": "3104857d-f658-429e-b5d8-d6a73c8c75e5",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "meetup",
         "name": "Meetup",

exercises/practice/matching-brackets/.docs/instructions.md

@@ -0,0 +1,5 @@
+# Instructions
+
+Given a string containing brackets `[]`, braces `{}`, parentheses `()`, or any combination thereof, verify that any and all pairs are matched and nested correctly.
+Any other characters should be ignored.
+For example, `"{what is (42)}?"` is balanced and `"[text}"` is not.

exercises/practice/matching-brackets/.docs/introduction.md

@@ -0,0 +1,8 @@
+# Introduction
+
+You're given the opportunity to write software for the Bracketeer™, an ancient but powerful mainframe.
+The software that runs on it is written in a proprietary language.
+Much of its syntax is familiar, but you notice _lots_ of brackets, braces and parentheses.
+Despite the Bracketeer™ being powerful, it lacks flexibility.
+If the source code has any unbalanced brackets, braces or parentheses, the Bracketeer™ crashes and must be rebooted.
+To avoid such a scenario, you start writing code that can verify that brackets, braces, and parentheses are balanced before attempting to run it on the Bracketeer™.

exercises/practice/matching-brackets/.gitignore

@@ -0,0 +1,11 @@
+## -*- conf -*-
+.rebar3
+_build/
+ebin/
+erl_crash.dump
+rebar3.crashdump
+
+tmp
+bin/configlet
+bin/configlet.exe
+CHECKLIST

exercises/practice/matching-brackets/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "src/matching-brackets.lfe"
+    ],
+    "test": [
+      "test/matching-brackets-tests.lfe"
+    ],
+    "example": [
+      ".meta/example.lfe"
+    ]
+  },
+  "blurb": "Make sure the brackets and braces all match.",
+  "source": "Ginna Baker"
+}

exercises/practice/matching-brackets/.meta/example.lfe

@@ -0,0 +1,33 @@
+(defmodule matching-brackets
+  (export (paired? 1)))
+
+(include-lib "lfe/include/clj.lfe")
+
+(defun paired? (string)
+  (paired-helper string '()))
+
+(defun paired-helper
+  (('() '())
+    'true)
+  (('() _)
+    'false)
+  (((cons #\{ string) stack)
+    (paired-helper string (cons #\{ stack)))
+  (((cons #\[ string) stack)
+    (paired-helper string (cons #\[ stack)))
+  (((cons #\( string) stack)
+    (paired-helper string (cons #\( stack)))
+  (((cons #\} string) (cons #\{ stack))
+    (paired-helper string stack))
+  (((cons #\] string) (cons #\[ stack))
+    (paired-helper string stack))
+  (((cons #\) string) (cons #\( stack))
+    (paired-helper string stack))
+  (((cons #\} _) _)
+    'false)
+  (((cons #\] _) _)
+    'false)
+  (((cons #\) _) _)
+    'false)
+  (((cons _ string) stack)
+    (paired-helper string stack)))

exercises/practice/matching-brackets/.meta/tests.toml

@@ -0,0 +1,70 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[81ec11da-38dd-442a-bcf9-3de7754609a5]
+description = "paired square brackets"
+
+[287f0167-ac60-4b64-8452-a0aa8f4e5238]
+description = "empty string"
+
+[6c3615a3-df01-4130-a731-8ef5f5d78dac]
+description = "unpaired brackets"
+
+[9d414171-9b98-4cac-a4e5-941039a97a77]
+description = "wrong ordered brackets"
+
+[f0f97c94-a149-4736-bc61-f2c5148ffb85]
+description = "wrong closing bracket"
+
+[754468e0-4696-4582-a30e-534d47d69756]
+description = "paired with whitespace"
+
+[ba84f6ee-8164-434a-9c3e-b02c7f8e8545]
+description = "partially paired brackets"
+
+[3c86c897-5ff3-4a2b-ad9b-47ac3a30651d]
+description = "simple nested brackets"
+
+[2d137f2c-a19e-4993-9830-83967a2d4726]
+description = "several paired brackets"
+
+[2e1f7b56-c137-4c92-9781-958638885a44]
+description = "paired and nested brackets"
+
+[84f6233b-e0f7-4077-8966-8085d295c19b]
+description = "unopened closing brackets"
+
+[9b18c67d-7595-4982-b2c5-4cb949745d49]
+description = "unpaired and nested brackets"
+
+[a0205e34-c2ac-49e6-a88a-899508d7d68e]
+description = "paired and wrong nested brackets"
+
+[1d5c093f-fc84-41fb-8c2a-e052f9581602]
+description = "paired and wrong nested brackets but innermost are correct"
+
+[ef47c21b-bcfd-4998-844c-7ad5daad90a8]
+description = "paired and incomplete brackets"
+
+[a4675a40-a8be-4fc2-bc47-2a282ce6edbe]
+description = "too many closing brackets"
+
+[a345a753-d889-4b7e-99ae-34ac85910d1a]
+description = "early unexpected brackets"
+
+[21f81d61-1608-465a-b850-baa44c5def83]
+description = "early mismatched brackets"
+
+[99255f93-261b-4435-a352-02bdecc9bdf2]
+description = "math expression"
+
+[8e357d79-f302-469a-8515-2561877256a1]
+description = "complex latex expression"

exercises/practice/matching-brackets/Makefile

@@ -0,0 +1,21 @@
+ERL    := $(shell which erl)
+REBAR3 := $(shell which rebar3)
+
+null  :=
+space := $(null) #
+comma := ,
+
+ifeq ($(ERL),)
+  $(error Can't find Erlang executable 'erl')
+else ifeq ($(REBAR3),)
+  $(error Can't find rebar3)
+endif
+
+compile: ; $(REBAR3) compile
+
+clean: ; $(REBAR3) clean
+
+.PHONY: test
+test:
+	$(REBAR3) eunit \
+	-m $(subst $(space),$(comma),$(basename $(notdir $(wildcard test/*.lfe))))

exercises/practice/matching-brackets/rebar.config

@@ -0,0 +1,11 @@
+{plugins, [{rebar3_lfe, "0.4.10"}]}.
+
+{provider_hooks, [{post, [{compile, {lfe, compile}}]}]}.
+
+{deps, [{lfe, "2.1.3"}]}.
+
+{profiles,
+ [{test,
+   [{eunit_compile_opts, [{src_dirs, ["src", "test"]}]},
+    {deps,
+     [{ltest, "0.13.8"}]}]}]}.

exercises/practice/matching-brackets/rebar.lock

@@ -0,0 +1,8 @@
+{"1.2.0",
+[{<<"lfe">>,{pkg,<<"lfe">>,<<"2.1.3">>},0}]}.
+[
+{pkg_hash,[
+ {<<"lfe">>, <<"6EFCB2BBC1FFC21DC5D1C092F00EFDB397EAC889474AC5C86EDF78A3557CC730">>}]},
+{pkg_hash_ext,[
+ {<<"lfe">>, <<"4E4BAD515A169AE418FEB7374EA1C8D741FAEA9D95E266CE343B45BCC377F55B">>}]}
+].

exercises/practice/matching-brackets/src/matching-brackets.app.src

@@ -0,0 +1,11 @@
+%% -*- erlang -*-
+{application, 'matching-brackets',
+ [{description, ""},
+  {vsn, "0.0.1"},
+  {modules,
+   ['matching-brackets']},
+  {registered, []},
+  {applications,
+   [kernel, stdlib]},
+  {included_applications, []},
+  {env, []}]}.

exercises/practice/matching-brackets/src/matching-brackets.lfe

@@ -0,0 +1,4 @@
+(defmodule matching-brackets
+  (export (paired? 1)))
+
+  ; Please implement the paired? function.

exercises/practice/matching-brackets/test/matching-brackets-tests.lfe

@@ -0,0 +1,66 @@
+(defmodule matching-brackets-tests
+  (behaviour ltest-unit)
+  (export all))
+
+(include-lib "ltest/include/ltest-macros.lfe")
+
+(deftest paired-square-brackets
+  (is (matching-brackets:paired? "[]")))
+
+(deftest empty-string
+  (is (matching-brackets:paired? "")))
+
+(deftest unpaired-brackets
+  (is-not (matching-brackets:paired? "[[")))
+
+(deftest wrong-ordered-brackets
+  (is-not (matching-brackets:paired? "}{")))
+
+(deftest wrong-closing-bracket
+  (is-not (matching-brackets:paired? "{]")))
+
+(deftest paired-with-whitespace
+  (is (matching-brackets:paired? "{ }")))
+
+(deftest partially-paired-brackets
+  (is-not (matching-brackets:paired? "{[])")))
+
+(deftest simple-nested-brackets
+  (is (matching-brackets:paired? "{[]}")))
+
+(deftest several-paired-brackets
+  (is (matching-brackets:paired? "{}[]")))
+
+(deftest paired-and-nested-brackets
+  (is (matching-brackets:paired? "([{}({}[])])")))
+
+(deftest unopened-closing-brackets
+  (is-not (matching-brackets:paired? "{[)][]}")))
+
+(deftest unpaired-and-nested-brackets
+  (is-not (matching-brackets:paired? "([{])")))
+
+(deftest paired-and-wrong-nested-brackets
+  (is-not (matching-brackets:paired? "[({]})")))
+
+(deftest paired-and-wrong-nested-brackets-but-innermost-are-correct
+  (is-not (matching-brackets:paired? "[({}])")))
+
+(deftest paired-and-incomplete-brackets
+  (is-not (matching-brackets:paired? "{}[")))
+
+(deftest too-many-closing-brackets
+  (is-not (matching-brackets:paired? "[]]")))
+
+(deftest early-unexpected-brackets
+  (is-not (matching-brackets:paired? ")()")))
+
+(deftest early-mismatched-brackets
+  (is-not (matching-brackets:paired? "{)()")))
+
+(deftest math-expression
+  (is (matching-brackets:paired? "(((185 + 223.85) * 15) - 543)/2")))
+
+(deftest complex-latex-expression
+  (let ((expr "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right)"))
+    (is (matching-brackets:paired? expr))))