Support interpolated strings in compiled content blocks

Closes #926

Author: willcosgrove

.rubocop.yml

@@ -3,6 +3,9 @@ inherit_from:
 
 AllCops:
   TargetRubyVersion: 3.2
+  Exclude:
+    - "quickdraw/compilation_equivalence_cases/**/*.rb"
+
 
 # We need to disable this cop because it’s not compatible with TruffleRuby 23.1, which still needs a `require "set"`
 Lint/RedundantRequireStatement:

comp_test.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require "phlex"
+
+class FlexHTML < Phlex::HTML
+	def view_template
+		__buffer__ = @_state.buffer; __buffer__ << "<h1></h1><h1>"
+		__yield_content__ { "Hello" }; __buffer__ << "</h1><div" \
+		<< __attributes__(class: "foo"); __buffer__ << "></div><div" \
+		<< __attributes__(class: "foo"); __buffer__ << ">"; __yield_content__ { "World" }; __buffer__ << "</div>"
+	end
+end
+
+puts FlexHTML.new.call

lib/phlex/compiler.rb

@@ -3,6 +3,8 @@
 require "prism"
 
 module Phlex::Compiler
+	Error = Class.new(StandardError)
+
 	def self.compile(component)
 		path, line = Object.const_source_location(component.name)
 		return unless File.exist?(path)

lib/phlex/compiler/method_compiler.rb

@@ -96,6 +96,8 @@ def visit_phlex_block(node)
 				case content
 				when Prism::StringNode
 					buffer(Phlex::Escape.html_escape(content.unescaped))
+				when Prism::InterpolatedStringNode
+					compile_interpolated_string_node(content)
 				else
 					raise
 				end
@@ -124,6 +126,31 @@ def compile_block_body_node(node)
 			]
 		end
 
+		def compile_interpolated_string_node(node)
+			node.parts.map do |part|
+				case part
+				when Prism::StringNode
+					buffer(Phlex::Escape.html_escape(part.unescaped))
+				when Prism::EmbeddedVariableNode
+					[
+						buffer('#{'),
+						buffer("::Phlex::Escape.html_escape(("),
+						buffer(part.variable.slice),
+						buffer(").to_s)}"),
+					]
+				when Prism::EmbeddedStatementsNode
+					[
+						buffer('#{'),
+						buffer("::Phlex::Escape.html_escape(("),
+						buffer(part.statements.slice, escape: false),
+						buffer(").to_s)}"),
+					]
+				else
+				  raise Phlex::Compiler::Error, "Unexpected node type in InterpolatedStringNode: #{part.class}"
+				end
+			end
+		end
+
 		def compile_void_element(node, tag)
 			[
 				[
@@ -217,19 +244,27 @@ def compile_raw_helper(node)
 			@current_buffer = nil
 		end
 
-		private def buffer(value)
+		private def buffer(value, escape: true)
 			if @current_buffer
-				@current_buffer << value
+				if escape
+					@current_buffer << value.gsub('"', '\\"')
+				else
+					@current_buffer << value
+				end
 				nil
 			else
 				new_buffer = +""
 				@current_buffer = new_buffer
-				new_buffer << value
+				if escape
+					new_buffer << value.gsub('"', '\\"')
+				else
+					new_buffer << value
+				end
 
 				[
 					:new_line,
 					"#{buffer_local} << \"",
-					-> { new_buffer.gsub('"', '\\"') },
+					new_buffer,
 					"\" if #{should_render_local}; nil;",
 				]
 			end
@@ -250,7 +285,7 @@ def compile_raw_helper(node)
 
 		private def content_block?(node)
 			return false unless node.body.body.length == 1
-			node.body.body.first in Prism::StringNode
+			node.body.body.first in Prism::StringNode | Prism::InterpolatedStringNode
 		end
 
 		private def standard_element?(node)

quickdraw/compilation_equivalence_cases/interpolated_string.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class InterpolatedString < Phlex::HTML
+	def view_template
+		name = "Joel"
+		@ivar = "Will"
+		h1 { "Hello, #{name}!" }
+		h2 { "Hello, #@ivar!" } # rubocop:disable Style/VariableInterpolation
+		h3 { "Hello #{"#{name}"}" }
+	end
+end