class Ameba::AST::ReachingDefinitionAnalyzer

Overview

Performs forward dataflow reaching-definition analysis on a scope's AST, the forward complement of LivenessAnalyzer: it answers "which variables already hold a definition that reaches a given program point?".

The reaching set is snapshotted at every inner scope node (block, proc, def, ...), following execution order. At conditional joins the branches are merged by union, but a branch that ends in a flow command (return, next, break, raise, ...) cannot fall through, so its definitions are excluded from the merge.

Included Modules

Defined in:

ameba/ast/reaching_definition_analyzer.cr

Constructors

Instance Method Summary

Instance methods inherited from module Ameba::AST::Dataflow

scope_body(node) scope_body

Instance methods inherited from module Ameba::AST::Util

abort?(node) abort?, control_exp_code(node : Crystal::ControlExpression, code_lines) control_exp_code, dynamic_literal?(node) : Bool dynamic_literal?, each_inline_directive(source, &block : Crystal::Token, String, Array(String) -> _) each_inline_directive, exit?(node) exit?, flow_command?(node, in_loop) flow_command?, flow_expression?(node, in_loop = false) flow_expression?, has_arguments?(node) : Bool has_arguments?, has_block?(node) : Bool has_block?, has_short_block?(node, code_lines) has_short_block?, heredoc?(node : Crystal::ASTNode, source : Source) heredoc?, literal?(node) : Bool literal?, loop?(node) loop?, name_end_location(node) name_end_location, name_location(node) name_location, name_location_or(token : Crystal::Token, name, *, adjust_location_column_number = nil)
name_location_or(node : Crystal::ASTNode, *, adjust_location_column_number = nil) name_location_or, name_size(node) name_size, node_source(node, code_lines) node_source, nodoc?(node) nodoc?, operator_method?(node) operator_method?, operator_method_name?(name : String) operator_method_name?, path_name(node : Crystal::Path, *, include_global = true) : String path_name, path_named?(node, *names : String) : Bool path_named?, raise?(node) raise?, setter_method?(node) setter_method?, setter_method_name?(name : String) setter_method_name?, short_block?(node, code_lines) short_block?, source_between(loc, end_loc, code_lines) : String | Nil source_between, static_literal?(node) : Bool static_literal?, suffix?(node) suffix?, takes_arguments?(node) : Bool takes_arguments?

Constructor Detail

def self.new(scope : Scope, entry : DefinedSet) #

Creates a new analyzer for scope. entry is the set of variable names already defined when the scope is entered (its arguments plus any captured outer definitions).


Instance Method Detail

def inner_scope_definitions : Hash(UInt64, DefinedSet) #

Returns a mapping of each inner-scope node's object_id to the set of variable names that reach the point where that scope is introduced.