Initial commit. Passed tests.

.gitignore

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+*.gem
+*.rbc
+.bundle
+.config
+.yardoc
+Gemfile.lock
+InstalledFiles
+_yardoc
+coverage
+doc/
+lib/bundler/man
+pkg
+rdoc
+spec/reports
+test/tmp
+test/version_tmp
+tmp

Gemfile

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+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in lps.gemspec
+gemspec

Guardfile

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+# A sample Guardfile
+# More info at https://github.com/guard/guard#readme
+
+guard :test do
+  watch(%r{^test/test_.+\.rb$})
+end
+

LICENSE

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+Copyright (c) 2012 Junegunn Choi
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# LPS: Loops Per Second
+
+Rate-controlled loop execution.
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+    gem 'lps'
+
+And then execute:
+
+    $ bundle
+
+Or install it yourself as:
+
+    $ gem install lps
+
+## Usage
+
+```ruby
+    # - Loops 10 times per second
+    # - Loops for 10 seconds
+    now = Time.now
+    LPS.freq(10).while { Time.now - now < 10 }.loop { # do something }
+
+    # - Loops 10 times per second
+    # - Loops indefinitely
+    LPS.freq(10).loop { # do something }
+```
+
+## Breaking out of the loop
+
+```ruby
+    LPS.freq(10).loop { break if rand(10) == 0 }
+```
+
+## Falling behind
+
+With LPS, the given loop block is run synchronously,
+so if it takes longer than the calculated interval,
+it won't be possible to achieve the desired frequency.
+
+```ruby
+    12.times.map { |i| 1 << i }.each do |ps|
+      cnt = 0
+      now = Time.now
+      LPS.freq(ps).while { Time.now - now <= 1 }.loop { cnt += 1; sleep 0.01 }
+
+      puts [ps, cnt].join ' => '
+    end
+```
+
+```
+1 => 1
+2 => 2
+4 => 4
+8 => 8
+16 => 16
+32 => 32
+64 => 64
+128 => 98
+256 => 98
+512 => 99
+1024 => 97
+2048 => 98
+```
+
+## Contributing
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Added some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request

Rakefile

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+#!/usr/bin/env rake
+require "bundler/gem_tasks"
+require 'rake/testtask'
+Rake::TestTask.new(:test) do |test|
+  test.libs << 'lib' << 'test'
+  test.pattern = 'test/**/test_*.rb'
+  test.verbose = true
+end

lib/lps.rb

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+require "lps/version"
+
+class LPS
+  def self.freq freq
+    LPS.new :freq => freq
+  end
+
+  def self.while &cond
+    LPS.new :cond => cond
+  end
+
+  def freq freq
+    LPS.new(:freq => freq, :cond => @cond)
+  end
+
+  def while &cond
+    LPS.new(:freq => @freq, :cond => cond)
+  end
+
+  def loop &block
+    ret = nil
+    if @freq.nil?
+      while @cond.call
+        ret = block.call
+      end
+    else
+      sleep_interval = 1.0 / @freq
+
+      nt = Time.now
+      while @cond.call
+        nt += sleep_interval
+        ret = block.call
+
+        now  = Time.now
+        diff = nt - now
+
+        if diff > 0.01
+          sleep diff
+        elsif diff < 0
+          nt = now
+        end
+      end
+    end
+    ret
+  end
+
+  def initialize opts = {}
+    raise ArgumentError.new("Not a Hash") unless opts.is_a?(Hash)
+
+    @freq = opts[:freq]
+    raise ArgumentError.new(
+      "Frequency must be a positive number (or nil)") unless 
+          @freq.nil? || (@freq.is_a?(Numeric) && @freq > 0)
+
+    @cond = opts[:cond] || proc { true }
+    raise ArgumentError.new("Invalid condition block") unless
+        @cond.is_a?(Proc)
+  end
+end
+

lib/lps/version.rb

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+class LPS
+  VERSION = "0.0.1"
+end

lps.gemspec

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+# -*- encoding: utf-8 -*-
+require File.expand_path('../lib/lps/version', __FILE__)
+
+Gem::Specification.new do |gem|
+  gem.authors       = ["Junegunn Choi"]
+  gem.email         = ["junegunn.c@gmail.com"]
+  gem.description   = %q{Rate-controlled loop}
+  gem.summary       = %q{Rate-controlled loop}
+  gem.homepage      = "https://github.com/junegunn/lps"
+
+  gem.files         = `git ls-files`.split($\)
+  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.name          = "lps"
+  gem.require_paths = ["lib"]
+  gem.version       = LPS::VERSION
+
+  gem.add_development_dependency 'test-unit'
+  gem.add_development_dependency 'guard'
+  gem.add_development_dependency 'guard-test'
+end

test/test_lps.rb

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+#!/usr/bin/env ruby
+
+require 'rubygems'
+$LOAD_PATH.unshift File.join(File.dirname(__FILE__), '../lib')
+require 'lps'
+require 'test-unit'
+
+class TestLPS < Test::Unit::TestCase
+  def test_lps
+    duration = 3
+
+    [0.2, 10, 20].each do |ps|
+      cnt = 0
+
+      now = Time.now
+      LPS.while { Time.now - now <= duration }.freq(ps).loop { cnt += 1 }
+
+      expected = (duration * ps).to_i
+      # FIXME: naive assertion
+      assert (expected-1..expected+1).include?(cnt)
+    end
+  end
+
+  def test_no_frequency
+    cnt = 0
+    now = Time.now
+    LPS.while { Time.now - now <= 1 }.loop { cnt += 1 }
+    # FIXME: naive assertion
+    assert cnt > 1000
+  end
+
+  def test_non_positive_frequency
+    assert_raise(ArgumentError) { LPS.freq(0) }
+    assert_raise(ArgumentError) { LPS.freq(-1) }
+  end
+
+  def test_non_number_frequency
+    assert_raise(ArgumentError) { LPS.freq('freq') }
+  end
+
+  def test_non_proc_cond
+    assert_raise(ArgumentError) { LPS.while('freq') }
+  end
+
+  def test_return_value
+    cnt = 0
+    now = Time.now
+    ret = LPS.while { Time.now - now <= 1 }.loop { cnt += 1 }
+    assert_equal cnt, ret
+  end
+
+  def test_loop_break
+    cnt = 0
+    LPS.freq(100).loop { break if (cnt += 1) >= 50 }
+    assert_equal 50, cnt
+  end
+
+  def test_lps_high_freq
+    20.times.map { |i| 1 << i }.each do |ps|
+      cnt = 0
+
+      now = Time.now
+      LPS.freq(ps).while { Time.now - now <= 1 }.loop { cnt += 1 }
+
+      # TODO: need assertion
+      puts [ps, cnt].join ' => '
+    end
+  end
+end
+