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| 1 | +# frozen_string_literal: true |
| 2 | + |
| 3 | +module TRuby |
| 4 | + # Version-specific code transformation strategies |
| 5 | + # |
| 6 | + # @example |
| 7 | + # emitter = CodeEmitter.for_version("4.0") |
| 8 | + # result = emitter.transform(source) |
| 9 | + # |
| 10 | + module CodeEmitter |
| 11 | + # Factory method to get appropriate emitter for target Ruby version |
| 12 | + # |
| 13 | + # @param target_ruby [String] target Ruby version (e.g., "3.0", "4.0") |
| 14 | + # @return [Base] appropriate emitter instance |
| 15 | + def self.for_version(target_ruby) |
| 16 | + version = RubyVersion.parse(target_ruby) |
| 17 | + |
| 18 | + if version.numbered_parameters_raise_error? |
| 19 | + Ruby40.new(version) |
| 20 | + elsif version.supports_it_parameter? |
| 21 | + Ruby34.new(version) |
| 22 | + elsif version.supports_anonymous_block_forwarding? |
| 23 | + Ruby31.new(version) |
| 24 | + else |
| 25 | + Ruby30.new(version) |
| 26 | + end |
| 27 | + end |
| 28 | + |
| 29 | + # Base class for version-specific code emitters |
| 30 | + class Base |
| 31 | + attr_reader :version |
| 32 | + |
| 33 | + def initialize(version) |
| 34 | + @version = version |
| 35 | + end |
| 36 | + |
| 37 | + # Apply all transformations for this version |
| 38 | + # |
| 39 | + # @param source [String] source code to transform |
| 40 | + # @return [String] transformed source code |
| 41 | + def transform(source) |
| 42 | + result = source.dup |
| 43 | + result = transform_numbered_params(result) |
| 44 | + transform_block_forwarding(result) |
| 45 | + end |
| 46 | + |
| 47 | + # Transform numbered block parameters (_1, _2, etc.) |
| 48 | + # Default: no transformation |
| 49 | + # |
| 50 | + # @param source [String] source code |
| 51 | + # @return [String] transformed source code |
| 52 | + def transform_numbered_params(source) |
| 53 | + source |
| 54 | + end |
| 55 | + |
| 56 | + # Transform block forwarding syntax |
| 57 | + # Default: no transformation |
| 58 | + # |
| 59 | + # @param source [String] source code |
| 60 | + # @return [String] transformed source code |
| 61 | + def transform_block_forwarding(source) |
| 62 | + source |
| 63 | + end |
| 64 | + |
| 65 | + # Check if this version supports the `it` implicit block parameter |
| 66 | + # |
| 67 | + # @return [Boolean] |
| 68 | + def supports_it? |
| 69 | + false |
| 70 | + end |
| 71 | + |
| 72 | + # Check if numbered parameters raise NameError in this version |
| 73 | + # |
| 74 | + # @return [Boolean] |
| 75 | + def numbered_params_error? |
| 76 | + false |
| 77 | + end |
| 78 | + end |
| 79 | + |
| 80 | + # Ruby 3.0 emitter - baseline, no transformations |
| 81 | + class Ruby30 < Base |
| 82 | + # Ruby 3.0 uses standard syntax, no transformations needed |
| 83 | + end |
| 84 | + |
| 85 | + # Ruby 3.1+ emitter - supports anonymous block forwarding |
| 86 | + class Ruby31 < Base |
| 87 | + # Transform `def foo(&block) ... bar(&block)` to `def foo(&) ... bar(&)` |
| 88 | + # |
| 89 | + # Only transforms when the block parameter is ONLY used for forwarding, |
| 90 | + # not when it's called directly (e.g., block.call) |
| 91 | + def transform_block_forwarding(source) |
| 92 | + result = source.dup |
| 93 | + |
| 94 | + # Find method definitions with block parameters |
| 95 | + # Pattern: def method_name(&block_name) |
| 96 | + result.gsub!(/def\s+(\w+[?!=]?)\s*\(([^)]*?)&(\w+)\s*\)/) do |_match| |
| 97 | + method_name = ::Regexp.last_match(1) |
| 98 | + other_params = ::Regexp.last_match(2) |
| 99 | + block_name = ::Regexp.last_match(3) |
| 100 | + |
| 101 | + # Find the method body to check block usage |
| 102 | + method_start = ::Regexp.last_match.begin(0) |
| 103 | + remaining = result[method_start..] |
| 104 | + |
| 105 | + # Check if block is only used for forwarding (not called directly) |
| 106 | + if block_only_forwarded?(remaining, block_name) |
| 107 | + "def #{method_name}(#{other_params}&)" |
| 108 | + else |
| 109 | + "def #{method_name}(#{other_params}&#{block_name})" |
| 110 | + end |
| 111 | + end |
| 112 | + |
| 113 | + # Replace block forwarding calls with anonymous forwarding |
| 114 | + # This is a simplified approach - in practice we'd need proper scope tracking |
| 115 | + result.gsub!(/(\w+)\s*\(\s*&(\w+)\s*\)/) do |match| |
| 116 | + call_name = ::Regexp.last_match(1) |
| 117 | + ::Regexp.last_match(2) |
| 118 | + |
| 119 | + # Check if this block name was converted to anonymous |
| 120 | + if result.include?("def ") && result.include?("(&)") |
| 121 | + "#{call_name}(&)" |
| 122 | + else |
| 123 | + match |
| 124 | + end |
| 125 | + end |
| 126 | + |
| 127 | + result |
| 128 | + end |
| 129 | + |
| 130 | + private |
| 131 | + |
| 132 | + # Check if a block parameter is only used for forwarding |
| 133 | + def block_only_forwarded?(method_body, block_name) |
| 134 | + # Simple heuristic: if block_name appears with .call or without &, it's not just forwarding |
| 135 | + # Look for patterns like: block_name.call, block_name.(), yield |
| 136 | + |
| 137 | + # Extract method body (until next def or end of class) |
| 138 | + lines = method_body.lines |
| 139 | + depth = 0 |
| 140 | + body_lines = [] |
| 141 | + |
| 142 | + lines.each do |line| |
| 143 | + depth += 1 if line.match?(/\b(def|class|module|do|begin|case|if|unless|while|until)\b/) |
| 144 | + depth -= 1 if line.match?(/\bend\b/) |
| 145 | + body_lines << line |
| 146 | + break if depth <= 0 && body_lines.length > 1 |
| 147 | + end |
| 148 | + |
| 149 | + body = body_lines.join |
| 150 | + |
| 151 | + # Check for direct block usage |
| 152 | + return false if body.match?(/\b#{block_name}\s*\./) # block.call, block.(), etc. |
| 153 | + return false if body.match?(/\b#{block_name}\s*\[/) # block[args] |
| 154 | + return false if body.match?(/\byield\b/) # yield instead of forwarding |
| 155 | + |
| 156 | + # Only &block_name patterns - this is forwarding |
| 157 | + true |
| 158 | + end |
| 159 | + end |
| 160 | + |
| 161 | + # Ruby 3.4+ emitter - supports `it` implicit block parameter |
| 162 | + class Ruby34 < Ruby31 |
| 163 | + def supports_it? |
| 164 | + true |
| 165 | + end |
| 166 | + |
| 167 | + # Ruby 3.4 still supports _1 syntax, so no transformation needed by default |
| 168 | + # Users can opt-in to using `it` style if they want |
| 169 | + end |
| 170 | + |
| 171 | + # Ruby 4.0+ emitter - _1 raises NameError, must use `it` |
| 172 | + class Ruby40 < Ruby34 |
| 173 | + def numbered_params_error? |
| 174 | + true |
| 175 | + end |
| 176 | + |
| 177 | + # Transform numbered parameters to appropriate syntax |
| 178 | + # |
| 179 | + # - Single _1 → it |
| 180 | + # - Multiple (_1, _2) → explicit |k, v| params |
| 181 | + def transform_numbered_params(source) |
| 182 | + result = source.dup |
| 183 | + |
| 184 | + # Simple approach: replace all _1 with it when it's the only numbered param in scope |
| 185 | + # For complex cases with _2+, we'd need proper parsing |
| 186 | + # For now, do a global replacement if _2 etc are not present |
| 187 | + if result.match?(/\b_[2-9]\b/) |
| 188 | + # Has multiple numbered params - need to convert to explicit params |
| 189 | + # This is a complex case that requires proper block parsing |
| 190 | + transform_multi_numbered_params(result) |
| 191 | + else |
| 192 | + # Only _1 is used - simple replacement |
| 193 | + result.gsub(/\b_1\b/, "it") |
| 194 | + end |
| 195 | + end |
| 196 | + |
| 197 | + private |
| 198 | + |
| 199 | + def transform_multi_numbered_params(source) |
| 200 | + result = source.dup |
| 201 | + |
| 202 | + # Find blocks and transform them |
| 203 | + # Use a recursive approach with placeholder replacement |
| 204 | + |
| 205 | + # Replace innermost blocks first |
| 206 | + loop do |
| 207 | + changed = false |
| 208 | + result = result.gsub(/\{([^{}]*)\}/) do |block| |
| 209 | + content = ::Regexp.last_match(1) |
| 210 | + max_param = find_max_numbered_param(content) |
| 211 | + |
| 212 | + if max_param > 1 |
| 213 | + # Multiple params - convert to explicit |
| 214 | + param_names = generate_param_names(max_param) |
| 215 | + new_content = content.dup |
| 216 | + (1..max_param).each do |i| |
| 217 | + new_content.gsub!(/\b_#{i}\b/, param_names[i - 1]) |
| 218 | + end |
| 219 | + changed = true |
| 220 | + "{ |#{param_names.join(", ")}| #{new_content.strip} }" |
| 221 | + elsif max_param == 1 |
| 222 | + # Single _1 - convert to it |
| 223 | + changed = true |
| 224 | + "{ #{content.gsub(/\b_1\b/, "it").strip} }" |
| 225 | + else |
| 226 | + block |
| 227 | + end |
| 228 | + end |
| 229 | + break unless changed |
| 230 | + end |
| 231 | + |
| 232 | + result |
| 233 | + end |
| 234 | + |
| 235 | + def find_max_numbered_param(content) |
| 236 | + max = 0 |
| 237 | + content.scan(/\b_(\d+)\b/) do |match| |
| 238 | + num = match[0].to_i |
| 239 | + max = num if num > max |
| 240 | + end |
| 241 | + max |
| 242 | + end |
| 243 | + |
| 244 | + def generate_param_names(count) |
| 245 | + # Generate simple parameter names: a, b, c, ... or k, v for 2 |
| 246 | + if count == 2 |
| 247 | + %w[k v] |
| 248 | + else |
| 249 | + ("a".."z").take(count) |
| 250 | + end |
| 251 | + end |
| 252 | + end |
| 253 | + end |
| 254 | +end |
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