--- /dev/null
+# 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.
+
+# Check for error in regular expressions from string literals
+module regex_phase
+
+private import parser_util
+private import literal
+import modelize
+
+redef class ToolContext
+
+ # Phase checking for errors in regex
+ var regex_phase: Phase = new RegexPhase(self, [literal_phase])
+end
+
+private class RegexPhase
+ super Phase
+
+ redef fun process_nmodule(nmodule)
+ do
+ var visitor = new RegexVisitor(toolcontext)
+ nmodule.accept_regex_visitor visitor
+ end
+end
+
+private class RegexVisitor
+ super Visitor
+
+ var toolcontext: ToolContext
+
+ redef fun visit(n) do n.accept_regex_visitor(self)
+end
+
+redef class ANode
+ private fun accept_regex_visitor(v: RegexVisitor) do visit_all v
+end
+
+redef class ACallExpr
+
+ redef fun accept_regex_visitor(v)
+ do
+ var method = n_id
+ var receiver = n_expr
+
+ # Check only string literals on which `to_re` is called
+ if method.text == "to_re" and receiver isa AStringFormExpr then
+
+ # Retrieve regex source
+ var re_src = receiver.value
+ if re_src == null then return
+
+ # Check for errors by compiling it right now
+ var re = re_src.to_re
+ var error = re.compile
+ re.finalize
+
+ if error != null then
+ v.toolcontext.error(self.location, "Regex Error: " + error.to_s)
+ end
+ end
+ end
+end