Add Crystal::Repl#parse_and_interpret (#14138)

* Add Crystal::Repl#parse_and_interpret

* Use single EvalResult type

* skip if without_interpreter

spec/compiler/crystal/tools/repl_spec.cr

@@ -0,0 +1,20 @@
+{% skip_file if flag?(:without_interpreter) %}
+
+require "../../../spec_helper"
+
+private def success_value(result : Crystal::Repl::EvalResult) : Crystal::Repl::Value
+  result.warnings.infos.should be_empty
+  result.value.should_not be_nil
+end
+
+describe Crystal::Repl do
+  it "can parse and evaluate snippets" do
+    repl = Crystal::Repl.new
+    repl.prelude = "primitives"
+    repl.load_prelude
+
+    success_value(repl.parse_and_interpret("1 + 2")).value.should eq(3)
+    success_value(repl.parse_and_interpret("def foo; 1 + 2; end")).value.should eq(nil)
+    success_value(repl.parse_and_interpret("foo")).value.should eq(3)
+  end
+end

src/compiler/crystal/interpreter/repl.cr

@@ -22,15 +22,13 @@ class Crystal::Repl
       when "exit"
         break
       when .presence
-        parser = new_parser(expression)
-        parser.warnings.report(STDOUT)
+        result = parse_and_interpret(expression)
+        result.warnings.report(STDOUT)
 
-        node = parser.parse
-        next unless node
+        next unless result.value
 
-        value = interpret(node)
         print " => "
-        puts SyntaxHighlighter::Colorize.highlight!(value.to_s)
+        puts SyntaxHighlighter::Colorize.highlight!(result.value.to_s)
       end
     rescue ex : EscapingException
       print "Unhandled exception: "
@@ -44,6 +42,18 @@ class Crystal::Repl
     end
   end
 
+  record EvalResult, value : Value?, warnings : WarningCollection
+
+  def parse_and_interpret(expression : String) : EvalResult
+    parser = new_parser(expression)
+
+    node = parser.parse
+    return EvalResult.new(value: nil, warnings: parser.warnings) unless node
+
+    value = interpret(node)
+    return EvalResult.new(value: value, warnings: parser.warnings)
+  end
+
   def run_file(filename, argv)
     @interpreter.argv = argv
 
@@ -68,7 +78,7 @@ class Crystal::Repl
     interpret(exps)
   end
 
-  private def load_prelude
+  def load_prelude
     node = parse_prelude
 
     interpret_and_exit_on_error(node)