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# frozen_string_literal: true
module Prism
# This module is used for testing and debugging and is not meant to be used by
# consumers of this library.
module Debug
# A wrapper around a RubyVM::InstructionSequence that provides a more
# convenient interface for accessing parts of the iseq.
class ISeq # :nodoc:
attr_reader :parts
def initialize(parts)
@parts = parts
end
def type
parts[0]
end
def local_table
parts[10]
end
def instructions
parts[13]
end
def each_child
instructions.each do |instruction|
# Only look at arrays. Other instructions are line numbers or
# tracepoint events.
next unless instruction.is_a?(Array)
instruction.each do |opnd|
# Only look at arrays. Other operands are literals.
next unless opnd.is_a?(Array)
# Only look at instruction sequences. Other operands are literals.
next unless opnd[0] == "YARVInstructionSequence/SimpleDataFormat"
yield ISeq.new(opnd)
end
end
end
end
private_constant :ISeq
# :call-seq:
# Debug::cruby_locals(source) -> Array
#
# For the given source, compiles with CRuby and returns a list of all of the
# sets of local variables that were encountered.
def self.cruby_locals(source)
verbose, $VERBOSE = $VERBOSE, nil
begin
locals = []
stack = [ISeq.new(RubyVM::InstructionSequence.compile(source).to_a)]
while (iseq = stack.pop)
names = [*iseq.local_table]
names.map!.with_index do |name, index|
# When an anonymous local variable is present in the iseq's local
# table, it is represented as the stack offset from the top.
# However, when these are dumped to binary and read back in, they
# are replaced with the symbol :#arg_rest. To consistently handle
# this, we replace them here with their index.
if name == :"#arg_rest"
names.length - index + 1
else
name
end
end
locals << names
iseq.each_child { |child| stack << child }
end
locals
ensure
$VERBOSE = verbose
end
end
# Used to hold the place of a local that will be in the local table but
# cannot be accessed directly from the source code. For example, the
# iteration variable in a for loop or the positional parameter on a method
# definition that is destructured.
AnonymousLocal = Object.new
private_constant :AnonymousLocal
# :call-seq:
# Debug::prism_locals(source) -> Array
#
# For the given source, parses with prism and returns a list of all of the
# sets of local variables that were encountered.
def self.prism_locals(source)
locals = []
stack = [Prism.parse(source).value]
while (node = stack.pop)
case node
when BlockNode, DefNode, LambdaNode
names = node.locals
params = node.parameters
params = params&.parameters unless node.is_a?(DefNode)
# prism places parameters in the same order that they appear in the
# source. CRuby places them in the order that they need to appear
# according to their own internal calling convention. We mimic that
# order here so that we can compare properly.
if params
sorted = [
*params.requireds.map do |required|
if required.is_a?(RequiredParameterNode)
required.name
else
AnonymousLocal
end
end,
*params.optionals.map(&:name),
*((params.rest.name || :*) if params.rest && !params.rest.is_a?(ImplicitRestNode)),
*params.posts.map do |post|
if post.is_a?(RequiredParameterNode)
post.name
else
AnonymousLocal
end
end,
*params.keywords.grep(RequiredKeywordParameterNode).map(&:name),
*params.keywords.grep(OptionalKeywordParameterNode).map(&:name),
]
if params.keyword_rest.is_a?(ForwardingParameterNode)
sorted.push(:*, :&, :"...")
end
sorted << AnonymousLocal if params.keywords.any?
# Recurse down the parameter tree to find any destructured
# parameters and add them after the other parameters.
param_stack = params.requireds.concat(params.posts).grep(MultiTargetNode).reverse
while (param = param_stack.pop)
case param
when MultiTargetNode
param_stack.concat(param.rights.reverse)
param_stack << param.rest
param_stack.concat(param.lefts.reverse)
when RequiredParameterNode
sorted << param.name
when SplatNode
sorted << param.expression.name if param.expression
end
end
names = sorted.concat(names - sorted)
end
names.map!.with_index do |name, index|
if name == AnonymousLocal
names.length - index + 1
else
name
end
end
locals << names
when ClassNode, ModuleNode, ProgramNode, SingletonClassNode
locals << node.locals
when ForNode
locals << [2]
when PostExecutionNode
locals.push([], [])
when InterpolatedRegularExpressionNode
locals << [] if node.once?
end
stack.concat(node.compact_child_nodes)
end
locals
end
# :call-seq:
# Debug::newlines(source) -> Array
#
# For the given source string, return the byte offsets of every newline in
# the source.
def self.newlines(source)
Prism.parse(source).source.offsets
end
end
end
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