Add ArrayLiteral#* and StringLiteral#* (#16154)

Co-authored-by: jneen <[email protected]>

Author: jneen

spec/compiler/macro/macro_methods_spec.cr

@@ -422,6 +422,10 @@ module Crystal
         assert_macro %({{"foo" != "bar"}}), %(true)
       end
 
+      it "executes string * number" do
+        assert_macro %({{"odelay" * 3}}), "\"odelayodelayodelay\""
+      end
+
       it "executes split without arguments" do
         assert_macro %({{"1 2 3".split}}), %(["1", "2", "3"] of ::String)
       end
@@ -768,6 +772,10 @@ module Crystal
         assert_macro %({{[1, 2, 3].map { |e| e == 2 }}}), "[false, true, false]"
       end
 
+      it "executes *" do
+        assert_macro %({{["na"] * 5}}), %(["na", "na", "na", "na", "na"])
+      end
+
       it "executes reduce with no initial value" do
         assert_macro %({{[1, 2, 3].reduce { |acc, val| acc * val }}}), "6"
       end

src/compiler/crystal/macros.cr

@@ -653,6 +653,10 @@ module Crystal::Macros
     # Similar to `String#<`
     def <(other : StringLiteral | MacroId) : BoolLiteral
     end
+
+    # Similar to `String#*`.
+    def *(other : NumberLiteral) : StringLiteral
+    end
   end
 
   # An interpolated string like `"Hello, #{name}!"`.
@@ -802,6 +806,10 @@ module Crystal::Macros
     def -(other : ArrayLiteral) : ArrayLiteral
     end
 
+    # Similar to `Array#*`
+    def *(other : NumberLiteral) : ArrayLiteral
+    end
+
     # Returns the type specified at the end of the array literal, if any.
     #
     # This refers to the part after brackets in `[] of String`.

src/compiler/crystal/macros/methods.cr

@@ -691,6 +691,20 @@ module Crystal
           end
           StringLiteral.new(@value + piece)
         end
+      when "*"
+        interpret_check_args do |arg|
+          unless arg.is_a?(Crystal::NumberLiteral)
+            arg.raise "argument to StringLiteral#* must be a number, not #{arg.class_desc}"
+          end
+
+          num = arg.to_number
+
+          unless num.is_a?(Int)
+            arg.raise "argument to StringLiteral#* cannot be a float"
+          end
+
+          StringLiteral.new(@value * num)
+        end
       when "camelcase"
         interpret_check_args(named_params: ["lower"]) do
           lower = if named_args && (lower_arg = named_args["lower"]?)
@@ -3169,6 +3183,20 @@ private def interpret_array_or_tuple_method(object, klass, method, args, named_a
       end
       klass.new(object.elements - other_elements)
     end
+  when "*"
+    interpret_check_args(node: object) do |arg|
+      unless arg.is_a?(Crystal::NumberLiteral)
+        arg.raise "argument to ArrayLiteral#* must be a number, not #{arg.class_desc}"
+      end
+
+      num = arg.to_number
+
+      unless num.is_a?(Int)
+        arg.raise "argument to ArrayLiteral#* cannot be a float"
+      end
+
+      klass.new(object.elements * num)
+    end
   else
     nil
   end