awk: new :fields feature for named fields.

* stdlib/awk.tl (sys:awk-compile-time): New slot, field-names.
(sys:awk-expander): Validate and store field-names into compile-time
structure.
(sys:awk-symac-let): New macro.
(awk): Wrap sys:awk-symac-let around code to generate field
name macros.

* tests/015/awk-fields.tl: New file.

* txr.1: Documented.

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/015/awk-fields.tl b/tests/015/awk-fields.tl
new file mode 100644
index 00000000..7f27e9e4
--- /dev/null
+++ b/tests/015/awk-fields.tl
@@ -0,0 +1,18 @@
+(load "../common")
+
+(mtest
+  (awk (:fields) (:begin (return-from awk))) nil
+  (awk (:fields t) (:begin (return-from awk))) :error
+  (awk (:fields nil) (:begin (return-from awk))) :error
+  (awk (:fields - -) (:begin (return-from awk))) nil
+  (awk (:fields a - - b) (:begin (return-from awk))) nil
+  (awk (:fields a - - a) (:begin (return-from awk))) :error
+  (awk (:fields a) (:fields b) (:begin (return-from awk))) :error)
+
+(test
+  (build
+    (awk
+      (:inputs '("How now brown cow"))
+      (:fields h n - c)
+      (t (add h n c))))
+  ("How" "now" "cow"))