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authorDmitry Ilyin <dilyin@mirantis.com>2015-09-01 21:39:16 +0300
committerDmitry Ilyin <dilyin@mirantis.com>2015-09-01 21:45:44 +0300
commit823a352f0f47d4481844bb6b6a6c00224ed556b8 (patch)
treea8224d823ec61c69d6364dc2b65e4afa138a1590
parentf820bb156038f638d8e488286d0c2b92c5636925 (diff)
Add a new function "try_get_value"
* Extracts a value from a deeply-nested data structure * Returns default if a value could not be extracted
-rw-r--r--README.markdown34
-rw-r--r--lib/puppet/parser/functions/try_get_value.rb77
-rwxr-xr-xspec/acceptance/try_get_value_spec.rb47
-rw-r--r--spec/functions/try_get_value_spec.rb100
4 files changed, 258 insertions, 0 deletions
diff --git a/README.markdown b/README.markdown
index 8ed3d9b..22bece8 100644
--- a/README.markdown
+++ b/README.markdown
@@ -669,6 +669,40 @@ Returns the current Unix epoch time as an integer. For example, `time()` returns
Converts the argument into bytes, for example "4 kB" becomes "4096". Takes a single string value as an argument. *Type*: rvalue.
+#### `try_get_value`
+
+*Type*: rvalue.
+
+Looks up into a complex structure of arrays and hashes and returns a value
+or the default value if nothing was found.
+
+Key can contain slashes to describe path components. The function will go down
+the structure and try to extract the required value.
+
+$data = {
+ 'a' => {
+ 'b' => [
+ 'b1',
+ 'b2',
+ 'b3',
+ ]
+ }
+}
+
+$value = try_get_value($data, 'a/b/2', 'not_found', '/')
+=> $value = 'b3'
+
+a -> first hash key
+b -> second hash key
+2 -> array index starting with 0
+
+not_found -> (optional) will be returned if there is no value or the path did not match. Defaults to nil.
+/ -> (optional) path delimiter. Defaults to '/'.
+
+In addition to the required "key" argument, "try_get_value" accepts default
+argument. It will be returned if no value was found or a path component is
+missing. And the fourth argument can set a variable path separator.
+
#### `type3x`
Returns a string description of the type when passed a value. Type can be a string, array, hash, float, integer, or boolean. This function will be removed when Puppet 3 support is dropped and the new type system can be used. *Type*: rvalue.
diff --git a/lib/puppet/parser/functions/try_get_value.rb b/lib/puppet/parser/functions/try_get_value.rb
new file mode 100644
index 0000000..0c19fd9
--- /dev/null
+++ b/lib/puppet/parser/functions/try_get_value.rb
@@ -0,0 +1,77 @@
+module Puppet::Parser::Functions
+ newfunction(
+ :try_get_value,
+ :type => :rvalue,
+ :arity => -2,
+ :doc => <<-eos
+Looks up into a complex structure of arrays and hashes and returns a value
+or the default value if nothing was found.
+
+Key can contain slashes to describe path components. The function will go down
+the structure and try to extract the required value.
+
+$data = {
+ 'a' => {
+ 'b' => [
+ 'b1',
+ 'b2',
+ 'b3',
+ ]
+ }
+}
+
+$value = try_get_value($data, 'a/b/2', 'not_found', '/')
+=> $value = 'b3'
+
+a -> first hash key
+b -> second hash key
+2 -> array index starting with 0
+
+not_found -> (optional) will be returned if there is no value or the path did not match. Defaults to nil.
+/ -> (optional) path delimiter. Defaults to '/'.
+
+In addition to the required "key" argument, "try_get_value" accepts default
+argument. It will be returned if no value was found or a path component is
+missing. And the fourth argument can set a variable path separator.
+ eos
+ ) do |args|
+ path_lookup = lambda do |data, path, default|
+ debug "Try_get_value: #{path.inspect} from: #{data.inspect}"
+ if data.nil?
+ debug "Try_get_value: no data, return default: #{default.inspect}"
+ break default
+ end
+ unless path.is_a? Array
+ debug "Try_get_value: wrong path, return default: #{default.inspect}"
+ break default
+ end
+ unless path.any?
+ debug "Try_get_value: value found, return data: #{data.inspect}"
+ break data
+ end
+ unless data.is_a? Hash or data.is_a? Array
+ debug "Try_get_value: incorrect data, return default: #{default.inspect}"
+ break default
+ end
+
+ key = path.shift
+ if data.is_a? Array
+ begin
+ key = Integer key
+ rescue ArgumentError
+ debug "Try_get_value: non-numeric path for an array, return default: #{default.inspect}"
+ break default
+ end
+ end
+ path_lookup.call data[key], path, default
+ end
+
+ data = args[0]
+ path = args[1] || ''
+ default = args[2]
+ separator = args[3] || '/'
+
+ path = path.split separator
+ path_lookup.call data, path, default
+ end
+end
diff --git a/spec/acceptance/try_get_value_spec.rb b/spec/acceptance/try_get_value_spec.rb
new file mode 100755
index 0000000..46b1c4d
--- /dev/null
+++ b/spec/acceptance/try_get_value_spec.rb
@@ -0,0 +1,47 @@
+#! /usr/bin/env ruby -S rspec
+require 'spec_helper_acceptance'
+
+describe 'try_get_value function', :unless => UNSUPPORTED_PLATFORMS.include?(fact('operatingsystem')) do
+ describe 'success' do
+ it 'try_get_valuees a value' do
+ pp = <<-EOS
+ $data = {
+ 'a' => { 'b' => 'passing'}
+ }
+
+ $tests = try_get_value($a, 'a/b')
+ notice(inline_template('tests are <%= @tests.inspect %>'))
+ EOS
+
+ apply_manifest(pp, :catch_failures => true) do |r|
+ expect(r.stdout).to match(/tests are "passing"/)
+ end
+ end
+ end
+ describe 'failure' do
+ it 'uses a default value' do
+ pp = <<-EOS
+ $data = {
+ 'a' => { 'b' => 'passing'}
+ }
+
+ $tests = try_get_value($a, 'c/d', 'using the default value')
+ notice(inline_template('tests are <%= @tests.inspect %>'))
+ EOS
+
+ apply_manifest(pp, :expect_failures => true) do |r|
+ expect(r.stdout).to match(/using the default value/)
+ end
+ end
+
+ it 'raises error on incorrect number of arguments' do
+ pp = <<-EOS
+ $o = try_get_value()
+ EOS
+
+ apply_manifest(pp, :expect_failures => true) do |r|
+ expect(r.stderr).to match(/wrong number of arguments/i)
+ end
+ end
+ end
+end
diff --git a/spec/functions/try_get_value_spec.rb b/spec/functions/try_get_value_spec.rb
new file mode 100644
index 0000000..38c0efd
--- /dev/null
+++ b/spec/functions/try_get_value_spec.rb
@@ -0,0 +1,100 @@
+require 'spec_helper'
+
+describe 'try_get_value' do
+
+ let(:data) do
+ {
+ 'a' => {
+ 'g' => '2',
+ 'e' => [
+ 'f0',
+ 'f1',
+ {
+ 'x' => {
+ 'y' => 'z'
+ }
+ },
+ 'f3',
+ ]
+ },
+ 'b' => true,
+ 'c' => false,
+ 'd' => '1',
+ }
+ end
+
+ context 'single values' do
+ it 'should exist' do
+ is_expected.not_to eq(nil)
+ end
+
+ it 'should be able to return a single value' do
+ is_expected.to run.with_params('test').and_return('test')
+ end
+
+ it 'should use the default value if data is a single value and path is present' do
+ is_expected.to run.with_params('test', 'path', 'default').and_return('default')
+ end
+
+ it 'should return default if there is no data' do
+ is_expected.to run.with_params(nil, nil, 'default').and_return('default')
+ end
+
+ it 'should be able to use data structures as default values' do
+ is_expected.to run.with_params('test', 'path', data).and_return(data)
+ end
+ end
+
+ context 'structure values' do
+ it 'should be able to extracts a single hash value' do
+ is_expected.to run.with_params(data, 'd', 'default').and_return('1')
+ end
+
+ it 'should be able to extract a deeply nested hash value' do
+ is_expected.to run.with_params(data, 'a/g', 'default').and_return('2')
+ end
+
+ it 'should return the default value if the path is not found' do
+ is_expected.to run.with_params(data, 'missing', 'default').and_return('default')
+ end
+
+ it 'should return the default value if the path is too long' do
+ is_expected.to run.with_params(data, 'a/g/c/d', 'default').and_return('default')
+ end
+
+ it 'should support an array index in the path' do
+ is_expected.to run.with_params(data, 'a/e/1', 'default').and_return('f1')
+ end
+
+ it 'should return the default value if an array index is not a number' do
+ is_expected.to run.with_params(data, 'a/b/c', 'default').and_return('default')
+ end
+
+ it 'should return the default value if and index is out of array length' do
+ is_expected.to run.with_params(data, 'a/e/5', 'default').and_return('default')
+ end
+
+ it 'should be able to path though both arrays and hashes' do
+ is_expected.to run.with_params(data, 'a/e/2/x/y', 'default').and_return('z')
+ end
+
+ it 'should be able to return "true" value' do
+ is_expected.to run.with_params(data, 'b', 'default').and_return(true)
+ is_expected.to run.with_params(data, 'm', true).and_return(true)
+ end
+
+ it 'should be able to return "false" value' do
+ is_expected.to run.with_params(data, 'c', 'default').and_return(false)
+ is_expected.to run.with_params(data, 'm', false).and_return(false)
+ end
+
+ it 'should return "nil" if value is not found and no default value is provided' do
+ is_expected.to run.with_params(data, 'a/1').and_return(nil)
+ end
+
+ it 'should be able to use a custom path separator' do
+ is_expected.to run.with_params(data, 'a::g', 'default', '::').and_return('2')
+ is_expected.to run.with_params(data, 'a::c', 'default', '::').and_return('default')
+ end
+ end
+end