Add O(1) lookup methods to Visitor

`code_line.rb` was calling `visitor.consecutive_lines.include?` which
is an O(n) array scan inside an O(n) loop over source lines — O(n²)
total. `token.rb` was calling
`visitor.endless_def_keyword_locs.include?` which is O(n) per token.

Add `consecutive_line?(line)` backed by the existing hash for O(1)
lookup, and `endless_def_loc?(location)` backed by a new hash keyed
on `start_offset` for O(1) lookup.

Freeze both hashes after `visit` to signal they are read-only after
construction.

Author: schneems

lib/syntax_suggest/code_line.rb

@@ -43,7 +43,7 @@ def self.from_source(source)
           line: line,
           index: index,
           tokens: tokens_for_line[index + 1],
-          consecutive: visitor.consecutive_lines.include?(index + 1)
+          consecutive: visitor.consecutive_line?(index + 1)
         )
       end
     end

lib/syntax_suggest/token.rb

@@ -29,7 +29,7 @@ def initialize(prism_token, previous_prism_token, visitor)
       # Prism lexes `:module` as SYMBOL_BEGIN, KEYWORD_MODULE
       # https://github.com/ruby/prism/issues/3940
       symbol_content = previous_prism_token&.type == :SYMBOL_BEGIN
-      @is_kw = KW_TYPES.include?(@type) && !symbol_content && !visitor.endless_def_keyword_locs.include?(@location)
+      @is_kw = KW_TYPES.include?(@type) && !symbol_content && !visitor.endless_def_loc?(@location)
       @is_end = @type == :KEYWORD_END
     end
 

lib/syntax_suggest/visitor.rb

@@ -34,16 +34,27 @@ class Visitor < Prism::Visitor
 
     def initialize
       @endless_def_keyword_locs = []
+      @endless_def_offsets = {}
       @consecutive_lines_hash = {}
       @consecutive_lines = []
     end
 
     def visit(ast)
       super(ast)
       @consecutive_lines = @consecutive_lines_hash.keys.sort
+      @consecutive_lines_hash.freeze
+      @endless_def_offsets.freeze
       self
     end
 
+    def consecutive_line?(line)
+      @consecutive_lines_hash.key?(line)
+    end
+
+    def endless_def_loc?(location)
+      @endless_def_offsets.key?(location.start_offset)
+    end
+
     # Called by Prism::Visitor for every method-call node in the AST
     # (e.g. `foo.bar`, `foo.bar.baz`).
     def visit_call_node(node)
@@ -77,7 +88,10 @@ def visit_call_node(node)
     # like `def foo = 123`. These are valid without a matching `end`,
     # so Token must exclude them when deciding if a line is a keyword.
     def visit_def_node(node)
-      @endless_def_keyword_locs << node.def_keyword_loc if node.equal_loc
+      if node.equal_loc
+        @endless_def_keyword_locs << node.def_keyword_loc
+        @endless_def_offsets[node.def_keyword_loc.start_offset] = true
+      end
       super
     end
   end