ccwl: Add conditions.

We introduce the &ccwl-violation condition. In later commits, it will
be used to indicate ccwl syntax violations and to print out useful
compiler errors.

* ccwl/conditions.scm: New file.

1 files changed, 39 insertions, 0 deletions

diff --git a/ccwl/conditions.scm b/ccwl/conditions.scm
new file mode 100644
index 0000000..756b46b
--- /dev/null
+++ b/ccwl/conditions.scm
@@ -0,0 +1,39 @@
+;;; ccwl --- Concise Common Workflow Language
+;;; Copyright © 2022 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of ccwl.
+;;;
+;;; ccwl is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; ccwl is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with ccwl.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (ccwl conditions)
+  #:use-module (rnrs conditions)
+  #:use-module (srfi srfi-28)
+  #:export (ccwl-violation
+            ccwl-violation?
+            ccwl-violation-file
+            ccwl-violation-line
+            ccwl-violation-column))
+
+(define-condition-type &ccwl-violation &violation
+  make-ccwl-violation ccwl-violation?
+  (file ccwl-violation-file)
+  (line ccwl-violation-line)
+  (column ccwl-violation-column))
+
+(define (ccwl-violation x)
+  "Return &ccwl-violation condition for syntax X."
+  (let ((properties (syntax-source x)))
+    (make-ccwl-violation (assq-ref properties 'filename)
+                         (assq-ref properties 'line)
+                         (assq-ref properties 'column))))