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Original file line number | Diff line number | Diff line change |
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# frozen_string_literal: true | ||
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module YARP | ||
# A pattern is an object that wraps a Ruby pattern matching expression. The | ||
# expression would normally be passed to an `in` clause within a `case` | ||
# expression or a rightward assignment expression. For example, in the | ||
# following snippet: | ||
# | ||
# case node | ||
# in ConstantPathNode[ConstantReadNode[name: :YARP], ConstantReadNode[name: :Pattern]] | ||
# end | ||
# | ||
# the pattern is the `ConstantPathNode[...]` expression. | ||
# | ||
# The pattern gets compiled into an object that responds to #call by running | ||
# the #compile method. This method itself will run back through YARP to | ||
# parse the expression into a tree, then walk the tree to generate the | ||
# necessary callable objects. For example, if you wanted to compile the | ||
# expression above into a callable, you would: | ||
# | ||
# callable = YARP::Pattern.new("ConstantPathNode[ConstantReadNode[name: :YARP], ConstantReadNode[name: :Pattern]]").compile | ||
# callable.call(node) | ||
# | ||
# The callable object returned by #compile is guaranteed to respond to #call | ||
# with a single argument, which is the node to match against. It also is | ||
# guaranteed to respond to #===, which means it itself can be used in a `case` | ||
# expression, as in: | ||
# | ||
# case node | ||
# when callable | ||
# end | ||
# | ||
# If the query given to the initializer cannot be compiled into a valid | ||
# matcher (either because of a syntax error or because it is using syntax we | ||
# do not yet support) then a YARP::Pattern::CompilationError will be | ||
# raised. | ||
class Pattern | ||
# Raised when the query given to a pattern is either invalid Ruby syntax or | ||
# is using syntax that we don't yet support. | ||
class CompilationError < StandardError | ||
def initialize(repr) | ||
super(<<~ERROR) | ||
YARP was unable to compile the pattern you provided into a usable | ||
expression. It failed on to understand the node represented by: | ||
#{repr} | ||
Note that not all syntax supported by Ruby's pattern matching syntax | ||
is also supported by YARP's patterns. If you're using some syntax | ||
that you believe should be supported, please open an issue on | ||
GitHub at https://github.com/ruby/yarp/issues/new. | ||
ERROR | ||
end | ||
end | ||
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attr_reader :query | ||
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def initialize(query) | ||
@query = query | ||
@compiled = nil | ||
end | ||
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def compile | ||
result = YARP.parse("case nil\nin #{query}\nend") | ||
compile_node(result.value.statements.body.last.conditions.last.pattern) | ||
end | ||
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def scan(root) | ||
return to_enum(__method__, root) unless block_given? | ||
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@compiled ||= compile | ||
queue = [root] | ||
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while (node = queue.shift) | ||
yield node if @compiled.call(node) | ||
queue.concat(node.child_nodes.compact) | ||
end | ||
end | ||
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private | ||
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# Shortcut for combining two procs into one that returns true if both return | ||
# true. | ||
def combine_and(left, right) | ||
->(other) { left.call(other) && right.call(other) } | ||
end | ||
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# Shortcut for combining two procs into one that returns true if either | ||
# returns true. | ||
def combine_or(left, right) | ||
->(other) { left.call(other) || right.call(other) } | ||
end | ||
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# Raise an error because the given node is not supported. | ||
def compile_error(node) | ||
raise CompilationError, node.inspect | ||
end | ||
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# in [foo, bar, baz] | ||
def compile_array_pattern_node(node) | ||
compile_error(node) if !node.rest.nil? || node.posts.any? | ||
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constant = node.constant | ||
compiled_constant = compile_node(constant) if constant | ||
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preprocessed = node.requireds.map { |required| compile_node(required) } | ||
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compiled_requireds = ->(other) do | ||
deconstructed = other.deconstruct | ||
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deconstructed.length == preprocessed.length && | ||
preprocessed | ||
.zip(deconstructed) | ||
.all? { |(matcher, value)| matcher.call(value) } | ||
end | ||
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if compiled_constant | ||
combine_and(compiled_constant, compiled_requireds) | ||
else | ||
compiled_requireds | ||
end | ||
end | ||
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# in foo | bar | ||
def compile_alternation_pattern_node(node) | ||
combine_or(compile_node(node.left), compile_node(node.right)) | ||
end | ||
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# in YARP::ConstantReadNode | ||
def compile_constant_path_node(node) | ||
parent = node.parent | ||
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if parent.is_a?(ConstantReadNode) && parent.slice == "YARP" | ||
compile_node(node.child) | ||
else | ||
compile_error(node) | ||
end | ||
end | ||
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# in ConstantReadNode | ||
# in String | ||
def compile_constant_read_node(node) | ||
value = node.slice | ||
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if YARP.const_defined?(value, false) | ||
clazz = YARP.const_get(value) | ||
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->(other) { clazz === other } | ||
elsif Object.const_defined?(value, false) | ||
clazz = Object.const_get(value) | ||
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->(other) { clazz === other } | ||
else | ||
compile_error(node) | ||
end | ||
end | ||
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# in InstanceVariableReadNode[name: Symbol] | ||
# in { name: Symbol } | ||
def compile_hash_pattern_node(node) | ||
compile_error(node) unless node.kwrest.nil? | ||
compiled_constant = compile_node(node.constant) if node.constant | ||
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preprocessed = | ||
node.assocs.to_h do |assoc| | ||
[assoc.key.unescaped.to_sym, compile_node(assoc.value)] | ||
end | ||
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compiled_keywords = ->(other) do | ||
deconstructed = other.deconstruct_keys(preprocessed.keys) | ||
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preprocessed.all? do |keyword, matcher| | ||
deconstructed.key?(keyword) && matcher.call(deconstructed[keyword]) | ||
end | ||
end | ||
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if compiled_constant | ||
combine_and(compiled_constant, compiled_keywords) | ||
else | ||
compiled_keywords | ||
end | ||
end | ||
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# in nil | ||
def compile_nil_node(node) | ||
->(attribute) { attribute.nil? } | ||
end | ||
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# in /foo/ | ||
def compile_regular_expression_node(node) | ||
regexp = Regexp.new(node.unescaped, node.closing[1..]) | ||
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->(attribute) { regexp === attribute } | ||
end | ||
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# in "" | ||
# in "foo" | ||
def compile_string_node(node) | ||
string = node.unescaped | ||
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->(attribute) { string === attribute } | ||
end | ||
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# in :+ | ||
# in :foo | ||
def compile_symbol_node(node) | ||
symbol = node.unescaped.to_sym | ||
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->(attribute) { symbol === attribute } | ||
end | ||
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# Compile any kind of node. Dispatch out to the individual compilation | ||
# methods based on the type of node. | ||
def compile_node(node) | ||
case node | ||
when AlternationPatternNode | ||
compile_alternation_pattern_node(node) | ||
when ArrayPatternNode | ||
compile_array_pattern_node(node) | ||
when ConstantPathNode | ||
compile_constant_path_node(node) | ||
when ConstantReadNode | ||
compile_constant_read_node(node) | ||
when HashPatternNode | ||
compile_hash_pattern_node(node) | ||
when NilNode | ||
compile_nil_node(node) | ||
when RegularExpressionNode | ||
compile_regular_expression_node(node) | ||
when StringNode | ||
compile_string_node(node) | ||
when SymbolNode | ||
compile_symbol_node(node) | ||
else | ||
compile_error(node) | ||
end | ||
end | ||
end | ||
end |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,132 @@ | ||
# frozen_string_literal: true | ||
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require_relative "test_helper" | ||
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module YARP | ||
class PatternTest < Test::Unit::TestCase | ||
def test_invalid_syntax | ||
assert_raises(Pattern::CompilationError) { scan("", "<>") } | ||
end | ||
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def test_invalid_constant | ||
assert_raises(Pattern::CompilationError) { scan("", "Foo") } | ||
end | ||
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def test_invalid_nested_constant | ||
assert_raises(Pattern::CompilationError) { scan("", "Foo::Bar") } | ||
end | ||
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def test_regexp_with_interpolation | ||
assert_raises(Pattern::CompilationError) { scan("", "/\#{foo}/") } | ||
end | ||
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def test_string_with_interpolation | ||
assert_raises(Pattern::CompilationError) { scan("", '"#{foo}"') } | ||
end | ||
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def test_symbol_with_interpolation | ||
assert_raises(Pattern::CompilationError) { scan("", ":\"\#{foo}\"") } | ||
end | ||
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def test_invalid_node | ||
assert_raises(Pattern::CompilationError) { scan("", "IntegerNode[^foo]") } | ||
end | ||
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def test_self | ||
assert_raises(Pattern::CompilationError) { scan("", "self") } | ||
end | ||
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def test_array_pattern_no_constant | ||
results = scan("1 + 2", "[IntegerNode]") | ||
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assert_equal 1, results.length | ||
end | ||
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def test_array_pattern | ||
results = scan("1 + 2", "CallNode[name: \"+\", receiver: IntegerNode, arguments: [IntegerNode]]") | ||
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assert_equal 1, results.length | ||
end | ||
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def test_alternation_pattern | ||
results = scan("Foo + Bar + 1", "ConstantReadNode | IntegerNode") | ||
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assert_equal 3, results.length | ||
assert_equal 1, results.grep(IntegerNode).first.value | ||
end | ||
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def test_constant_read_node | ||
results = scan("Foo + Bar + Baz", "ConstantReadNode") | ||
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assert_equal 3, results.length | ||
assert_equal %w[Bar Baz Foo], results.map(&:slice).sort | ||
end | ||
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def test_object_const | ||
results = scan("1 + 2 + 3", "IntegerNode[]") | ||
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assert_equal 3, results.length | ||
end | ||
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def test_constant_path | ||
results = scan("Foo + Bar + Baz", "YARP::ConstantReadNode") | ||
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assert_equal 3, results.length | ||
end | ||
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def test_hash_pattern_no_constant | ||
results = scan("Foo + Bar + Baz", "{ name: \"+\" }") | ||
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assert_equal 2, results.length | ||
end | ||
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def test_hash_pattern_regexp | ||
results = scan("Foo + Bar + Baz", "{ name: /^[[:punct:]]$/ }") | ||
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assert_equal 2, results.length | ||
assert_equal ["YARP::CallNode"], results.map { |node| node.class.name }.uniq | ||
end | ||
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def test_nil | ||
results = scan("foo", "{ receiver: nil }") | ||
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assert_equal 1, results.length | ||
end | ||
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def test_regexp_options | ||
results = scan("@foo + @bar + @baz", "InstanceVariableReadNode[name: /^@B/i]") | ||
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assert_equal 2, results.length | ||
end | ||
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def test_string_empty | ||
results = scan("", "''") | ||
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assert_empty results | ||
end | ||
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def test_symbol_empty | ||
results = scan("", ":''") | ||
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assert_empty results | ||
end | ||
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def test_symbol_plain | ||
results = scan("@foo", "{ name: :\"@foo\" }") | ||
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assert_equal 1, results.length | ||
end | ||
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def test_symbol | ||
results = scan("@foo", "{ name: :@foo }") | ||
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assert_equal 1, results.length | ||
end | ||
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private | ||
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def scan(source, query) | ||
YARP::Pattern.new(query).scan(YARP.parse(source).value).to_a | ||
end | ||
end | ||
end |