ERB: Adds scanner based on Prism (#644)

- It is enabled by setting
search:
  prism: "rails" # or "ruby"

Author: davidwessman

CHANGES.md

@@ -17,6 +17,10 @@ search:
   prism: "ruby"
 ```
 to use the Prism Scanner without Rails support.
+- Implements ERB-scanner using Prism, activated with same config as above.
+  - The Prism-based scanner handles comments differently vs the `whitequark/parser`-based scanner does.
+  - The usage will be for the magic comment line instead of the subsequent line.
+  - This should not affect the results of the CLI tasks.
 
 ## v1.0.15
 

README.md

@@ -530,12 +530,13 @@ WATSONX_PROJECT_ID=<watsonx project id>
 WATSONX_MODEL=<optional>
 ```
 
-### Prism-based scanner
+### Prism-based scanner for Ruby and ERB files
 
 There is a scanner based on [Prism](https://github.com/ruby/prism) usable in two different modes.
 
 - `rails` mode parses Rails code and handles context such as controllers, before_actions, model translations and more.
 - `ruby` mode parses Ruby code only, and works similar to the existing whitequark/parser-implementation.
+- The parser is used for both ruby and ERB files.
 
 #### `rails` mode
 

lib/i18n/tasks/scanners/erb_ast_scanner.rb

@@ -2,15 +2,19 @@
 
 require "i18n/tasks/scanners/ruby_scanner"
 require "i18n/tasks/scanners/local_ruby_parser"
+require "i18n/tasks/scanners/occurrence_from_position"
+require "prism"
 
 module I18n::Tasks::Scanners
-  # Scan for I18n.translate calls in ERB-file better-html and ASTs
+  # Scan for I18n.translate calls in ERB-file using regexp and Parser/Prism
   class ErbAstScanner < RubyScanner
-    DEFAULT_REGEXP = /<%(={1,2}|-|\#|%)?(.*?)([-=])?%>/m
+    include OccurrenceFromPosition
+    DEFAULT_REGEXP = /<%(={1,2}|-|\#-?|%)?(.*?)([-=])?%>/m
 
-    def initialize(**args)
+    # Parser scanner, method called in RubyScanner
+    def ast_parser_parse_file(path)
+      @ruby_parser ||= LocalRubyParser.new(ignore_blocks: true)
       super
-      @ruby_parser = LocalRubyParser.new(ignore_blocks: true)
     end
 
     private
@@ -74,5 +78,59 @@ def root_node(children, buffer)
         )
       ::Parser::AST::Node.new(:erb, children, location: location)
     end
+
+    # Prism scanner, method called in RubyScanner
+    def prism_parse_file(path)
+      occurrences = []
+      content = File.read(path)
+
+      content.scan(DEFAULT_REGEXP) do |indicator, code, _tailch, _rspace|
+        match = Regexp.last_match
+        character = indicator ? indicator[0] : nil
+        start = match.begin(0) + 2 + (character&.size || 0)
+
+        case character
+        when "=", nil, "-"
+          occurrences += process_code(path, code, content, start)
+        when "#", "#-"
+          occurrences += process_comments(path, code, content, start)
+        end
+      end
+
+      occurrences
+    end
+
+    def process_code(path, code, content, start)
+      return [] if code.strip.empty? # skip empty ERB tags
+
+      process_prism_results(path, Prism.parse(code)).map do |key, occurrence|
+        [
+          key,
+          occurrence_from_position(
+            path,
+            content,
+            start + occurrence.pos,
+            raw_key: occurrence.raw_key
+          )
+        ]
+      end
+    end
+
+    def process_comments(path, code, content, start)
+      return [] if code.strip.empty?
+
+      parsed = Prism.parse(code.gsub("i18n-tasks-use ", "#i18n-tasks-use "))
+      process_prism_results(path, parsed).map do |key, occurrence|
+        [
+          key,
+          occurrence_from_position(
+            path,
+            content,
+            start + (code.index(key) || occurrence.pos),
+            raw_key: occurrence.raw_key
+          )
+        ]
+      end
+    end
   end
 end