Data commit

Task/S-expressions/Sidef/s-expressions.sidef

@@ -0,0 +1,50 @@
+func sexpr(txt) {
+    txt.trim!
+
+    if (txt.match(/^\((.*)\)$/s)) {|m|
+        txt = m[0]
+    }
+    else {
+        die "Invalid: <<#{txt}>>"
+    }
+
+    var w
+    var ret = []
+
+    while (!txt.is_empty) {
+        given (txt.first) {
+            when('(') {
+                (w, txt) = txt.extract_bracketed('()');
+                w = sexpr(w)
+            }
+            when ('"') {
+                (w, txt) = txt.extract_delimited('"')
+                w.sub!(/^"(.*)"/, {|s1| s1 })
+            }
+            else {
+                txt.sub!(/^(\S+)/, {|s1| w = s1; '' })
+            }
+        }
+        ret << w
+        txt.trim_beg!
+    }
+    return ret
+}
+
+func sexpr2txt(String e) {
+    e ~~ /[\s"\(\)]/ ? do { e.gsub!('"', '\\"'); %Q("#{e}") } : e
+}
+
+func sexpr2txt(expr) {
+    '(' + expr.map {|e| sexpr2txt(e) }.join(' ') + ')'
+}
+
+var s = sexpr(%q{
+
+((data "quoted data" 123 4.5)
+ (data (!@# (4.5) "(more" "data)")))
+
+})
+
+say s               # dump structure
+say sexpr2txt(s)    # convert back