tasks a-s

Task/S-Expressions/Python/s-expressions-1.py

@@ -0,0 +1,60 @@
+import re
+
+dbg = False
+
+term_regex = r'''(?mx)
+    \s*(?:
+        (?P<brackl>\()|
+        (?P<brackr>\))|
+        (?P<num>\d+\.\d+|\d+)\b|
+        (?P<sq>"[^"]*")|
+        (?P<s>\S+)\b
+       )'''
+
+def parse_sexp(sexp):
+    stack = []
+    out = []
+    if dbg: print("%-6s %-14s %-44s %-s" % tuple("term value out stack".split()))
+    for termtypes in re.finditer(term_regex, sexp):
+        term, value = [(t,v) for t,v in termtypes.groupdict().items() if v][0]
+        if dbg: print("%-7s %-14s %-44r %-r" % (term, value, out, stack))
+        if   term == 'brackl':
+            stack.append(out)
+            out = []
+        elif term == 'brackr':
+            assert stack, "Trouble with nesting of brackets"
+            tmpout, out = out, stack.pop(-1)
+            out.append(tmpout)
+        elif term == 'num':
+            v = float(value)
+            if v.is_integer(): v = int(v)
+            out.append(v)
+        elif term == 'sq':
+            out.append(value[1:-1])
+        elif term == 's':
+            out.append(value)
+        else:
+            raise NotImplementedError("Error: %r" % (term, value))
+    assert not stack, "Trouble with nesting of brackets"
+    return out[0]
+
+def print_sexp(exp):
+    out = ''
+    if type(exp) == type([]):
+        out += '(' + ' '.join(print_sexp(x) for x in exp) + ')'
+    elif type(exp) == type('') and re.search(r'[\s()]', exp):
+        out += '"%s"' % repr(exp)[1:-1].replace('"', '\"')
+    else:
+        out += '%s' % exp
+    return out
+
+
+if __name__ == '__main__':
+    sexp = ''' ( ( data "quoted data" 123 4.5)
+         (data (123 (4.5) "(more" "data)")))'''
+
+    print('Input S-expression: %r' % (sexp, ))
+    parsed = parse_sexp(sexp)
+    print("\nParsed to Python:", parsed)
+
+    print("\nThen back to: '%s'" % print_sexp(parsed))

Task/S-Expressions/Python/s-expressions-2.py

@@ -0,0 +1,23 @@
+>>> from pprint import pprint as pp
+>>> x = [[(t,v) for t,v in  termtypes.groupdict().items() if v][0] for termtypes in re.finditer(term_regex, sexp)]
+>>> pp(x)
+[('brackl', '('),
+ ('brackl', '('),
+ ('s', 'data'),
+ ('sq', '"quoted data"'),
+ ('num', '123'),
+ ('num', '4.5'),
+ ('brackr', ')'),
+ ('brackl', '('),
+ ('s', 'data'),
+ ('brackl', '('),
+ ('num', '123'),
+ ('brackl', '('),
+ ('num', '4.5'),
+ ('brackr', ')'),
+ ('sq', '"(more"'),
+ ('sq', '"data)"'),
+ ('brackr', ')'),
+ ('brackr', ')'),
+ ('brackr', ')')]
+>>>