frontend: new phase `deriving` to derive things

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/frontend/check_annotation.nit b/src/frontend/check_annotation.nit
index 419c5ae..36244f6 100644 (file)
--- a/src/frontend/check_annotation.nit
+++ b/src/frontend/check_annotation.nit
@@ -91,6 +91,8 @@ intern
 extern
 no_warning
 
+auto_inspect
+
 pkgconfig
 cflags
 ldflags

diff --git a/src/frontend/deriving.nit b/src/frontend/deriving.nit
new file mode 100644 (file)
index 0000000..e04a4f4
--- /dev/null
+++ b/src/frontend/deriving.nit
@@ -0,0 +1,69 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Injection of automatic method definitions for standard methods, based on the attributes of the classes
+#
+# This phase is only a proof of concept and is inherently fragile:
+#
+# * syntactic code injection without semantic checking
+# * ignorance of name conflicts
+# * attributes are syntactically and locally collected
+module deriving
+
+private import parser_util
+import modelize
+private import annotation
+
+redef class ToolContext
+       # Main phase of `deriving`
+       var deriving_phase: Phase = new DerivingPhase(self, null)
+end
+
+private class DerivingPhase
+       super Phase
+
+       redef fun process_annotated_node(nclassdef, nat)
+       do
+               if nat.name == "auto_inspect" then
+                       if not nclassdef isa AStdClassdef then
+                               toolcontext.error(nclassdef.location, "Syntax error: only a concrete class can be `{nat.name}`.")
+                       else
+                               generate_inspect_method(nclassdef)
+                       end
+               end
+       end
+
+       fun generate_inspect_method(nclassdef: AClassdef)
+       do
+               var npropdefs = nclassdef.n_propdefs
+
+               var code = new Array[String]
+               code.add "redef fun inspect"
+               code.add "do"
+               code.add "      var res = super"
+               code.add "      res = res.substring(0,res.length-1)"
+
+               for attribute in npropdefs do if attribute isa AAttrPropdef then
+                       var name = attribute.n_id2.text
+                       code.add """    res += " {{{name}}}: {self.{{{name}}}.inspect}""""
+               end
+
+               code.add "      res += \">\""
+               code.add "      return res"
+               code.add "end"
+
+               # Create method Node and add it to the AST
+               npropdefs.push(toolcontext.parse_propdef(code.join("\n")))
+       end
+end

diff --git a/src/frontend/frontend.nit b/src/frontend/frontend.nit
index 8c5079f..9d39890 100644 (file)
--- a/src/frontend/frontend.nit
+++ b/src/frontend/frontend.nit
@@ -22,6 +22,7 @@ import modelize
 import semantize
 import div_by_zero
 import serialization_phase
+import deriving
 import check_annotation
 import glsl_validation