pib · November 23, 2009 07:57 · Nov 23, 2009
diff --git a/sexp.py b/sexp.py
@@ -0,0 +1,38 @@
+from string import whitespace
+
+atom_end = set('()"\'') | set(whitespace)
+
+def parse(sexp):
+    stack, i, length = [[]], 0, len(sexp)
+    while i < length:
+        c = sexp[i]
+
+        print c, stack
+        reading = type(stack[-1])
+        if reading == list:
+            if   c == '(': stack.append([])
+            elif c == ')': 
+                stack[-2].append(stack.pop())
+                if stack[-1][0] == ('quote',): stack[-2].append(stack.pop())
+            elif c == '"': stack.append('')
+            elif c == "'": stack.append([('quote',)])
+            elif c in whitespace: pass
+            else: stack.append((c,))
+        elif reading == str:
+            if   c == '"': 
+                stack[-2].append(stack.pop())
+                if stack[-1][0] == ('quote',): stack[-2].append(stack.pop())
+            elif c == '\\': 
+                i += 1
+                stack[-1] += sexp[i]
+            else: stack[-1] += c
+        elif reading == tuple:
+            if c in atom_end:
+                atom = stack.pop()
+                if atom[0][0].isdigit(): stack[-1].append(eval(atom[0]))
+                else: stack[-1].append(atom)
+                if stack[-1][0] == ('quote',): stack[-2].append(stack.pop())
+                continue
+            else: stack[-1] = ((stack[-1][0] + c),)
+        i += 1
+    return stack.pop()