From: Jean Privat <jean@pryen.org>
Date: Thu, 7 May 2015 01:56:08 +0000 (-0400)
Subject: Merge: Balanced brackets
X-Git-Tag: v0.7.5~76
X-Git-Url: http://nitlanguage.org?hp=ace6ea4a957ca05aa6ace7e928973b6a158ae74c

Merge: Balanced brackets

The PR started as a simple implementation for the task http://rosettacode.org/wiki/Balanced_brackets but some improvements on the lib and tests.sh where also added

Pull-Request: #1307
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
---

diff --git a/examples/rosettacode/balanced_brackets.nit b/examples/rosettacode/balanced_brackets.nit
new file mode 100644
index 0000000..a1ae476
--- /dev/null
+++ b/examples/rosettacode/balanced_brackets.nit
@@ -0,0 +1,39 @@
+#!/usr/bin/env nit
+#
+# This file is part of NIT ( http://www.nitlanguage.org ).
+# This program is public domain
+
+# Task: Balanced brackets
+# SEE: <http://rosettacode.org/wiki/Balanced_brackets>
+module balanced_brackets
+
+# Are `[` and `]` balanced?
+# Other characters are ignored.
+#
+#     assert is_balanced("[][[]]")
+#     assert is_balanced("")
+#     assert not is_balanced("[[]")
+#     assert not is_balanced("][][")
+fun is_balanced(s: String): Bool
+do
+	var l = 0
+	for x in s.chars do
+		if x == '[' then
+			l += 1
+		else if x == ']' then
+			l -= 1
+			if l < 0 then return false
+		end
+	end
+	return l == 0
+end
+
+var n = 3
+if args.not_empty then n = args.first.to_i
+
+for i in [0..10[ do
+	var a = (['[', ']'] * n)
+	a.shuffle
+	var b = a.join("")
+	if is_balanced(b) then print "{b} is well-balanced" else print "{b} is not well-balanced"
+end
diff --git a/lib/mnit/mnit_injected_input.nit b/lib/mnit/mnit_injected_input.nit
index 4d6ddfa..da2e33d 100644
--- a/lib/mnit/mnit_injected_input.nit
+++ b/lib/mnit/mnit_injected_input.nit
@@ -20,7 +20,7 @@
 # In order to reproduce executions, the behavior of the application must be deterministic
 # for a given sequence of inputs.
 # The main source of differences in executions is caused by the `rand` function,
-# Set the environment variable `MNIT_SRAND` to a value to force srand to be initialized with this value.
+# Set the environment variable `NIT_SRAND` to a value to force srand to be initialized with this value.
 #
 # The input event file is made of event descriptions, one event by line.
 #
@@ -75,13 +75,6 @@ redef class App
 
 	redef fun setup
 	do
-		var env = "MNIT_SRAND".environ
-		if env != "" then
-			srand_from(env.to_i)
-		else
-			srand_from(0)
-		end
-
 		var input = "MNIT_READ_INPUT".environ
 		if input != "" then
 			injected_input_stream = new FileReader.open(input)
diff --git a/lib/standard/environ.nit b/lib/standard/environ.nit
index 2f6ae46..0abe7f3 100644
--- a/lib/standard/environ.nit
+++ b/lib/standard/environ.nit
@@ -60,3 +60,11 @@ redef class NativeString
 	private fun get_environ: NativeString is extern "string_NativeString_NativeString_get_environ_0"
 	private fun setenv( v : NativeString ) is extern "string_NativeString_NativeString_setenv_1"
 end
+
+redef class Sys
+	redef init
+	do
+		var x = "NIT_SRAND".environ
+		if x != "" then srand_from(x.to_i)
+	end
+end
diff --git a/lib/standard/math.nit b/lib/standard/math.nit
index 2b55dca..9e1744f 100644
--- a/lib/standard/math.nit
+++ b/lib/standard/math.nit
@@ -241,6 +241,11 @@ end
 redef class Collection[ E ]
 	# Return a random element form the collection
 	# There must be at least one element in the collection
+	#
+	# ~~~
+	# var x = [1,2,3].rand
+	# assert x == 1 or x == 2 or x == 3
+	# ~~~
 	fun rand: E
 	do
 		if is_empty then abort
@@ -252,6 +257,19 @@ redef class Collection[ E ]
 		end
 		abort
 	end
+
+	# Return a new array made of elements in a random order.
+	#
+	# ~~~
+	# var a = [1,2,1].to_shuffle
+	# assert a == [1,1,2] or a == [1,2,1] or a == [2,1,1]
+	# ~~~
+	fun to_shuffle: Array[E]
+	do
+		var res = self.to_a
+		res.shuffle
+		return res
+	end
 end
 
 redef class SequenceRead[E]
@@ -263,6 +281,36 @@ redef class SequenceRead[E]
 	end
 end
 
+redef class AbstractArray[E]
+	# Reorder randomly the elements in self.
+	#
+	# ~~~
+	# var a = new Array[Int]
+	#
+	# a.shuffle
+	# assert a.is_empty
+	#
+	# a.add 1
+	# a.shuffle
+	# assert a == [1]
+	#
+	# a.add 2
+	# a.shuffle
+	# assert a == [1,2] or a == [2,1]
+	# ~~~
+	#
+	# ENSURE self.shuffle.has_exactly(old(self))
+	fun shuffle
+	do
+		for i in [0..length[ do
+			var j = i + (length-i).rand
+			var tmp = self[i]
+			self[i] = self[j]
+			self[j] = tmp
+		end
+	end
+end
+
 redef class Sys
 	init
 	do
diff --git a/tests/sav/balanced_brackets.res b/tests/sav/balanced_brackets.res
new file mode 100644
index 0000000..ea08659
--- /dev/null
+++ b/tests/sav/balanced_brackets.res
@@ -0,0 +1,10 @@
+][[]][ is not well-balanced
+[[]][] is well-balanced
+[]][][ is not well-balanced
+[[[]]] is well-balanced
+[][]][ is not well-balanced
+]][[][ is not well-balanced
+[]]][[ is not well-balanced
+[]][][ is not well-balanced
+[][][] is well-balanced
+][]][[ is not well-balanced
diff --git a/tests/tests.sh b/tests/tests.sh
index 39e0cbd..2769eba 100755
--- a/tests/tests.sh
+++ b/tests/tests.sh
@@ -21,7 +21,7 @@
 export LANG=C
 export LC_ALL=C
 export NIT_TESTING=true
-export MNIT_SRAND=0
+export NIT_SRAND=0
 
 unset NIT_DIR