1 files changed, 143 insertions, 0 deletions
diff --git a/codegen/scmexpr.py b/codegen/scmexpr.py
new file mode 100644
index 0000000..02f2e4b
--- /dev/null
+++ b/codegen/scmexpr.py
@@ -0,0 +1,143 @@
+#!/usr/bin/env python
+# -*- Mode: Python; py-indent-offset: 4 -*-
+from __future__ import generators
+
+import string
+from cStringIO import StringIO
+
+class error(Exception):
+    def __init__(self, filename, lineno, msg):
+        Exception.__init__(self, msg)
+        self.filename = filename
+        self.lineno = lineno
+        self.msg = msg
+    def __str__(self):
+        return '%s:%d: error: %s' % (self.filename, self.lineno, self.msg)
+
+trans = [' '] * 256
+for i in range(256):
+    if chr(i) in string.letters + string.digits + '_':
+        trans[i] = chr(i)
+    else:
+        trans[i] = '_'
+trans = string.join(trans, '')
+
+def parse(filename):
+    if isinstance(filename, str):
+        fp = open(filename, 'r')
+    else: # if not string, assume it is some kind of iterator
+        fp = filename
+        filename = getattr(fp, 'name', '<unknown>')
+    whitespace = ' \t\n\r\x0b\x0c'
+    nonsymbol = whitespace + '();\'"'
+    stack = []
+    openlines = []
+    lineno = 0
+    for line in fp:
+        pos = 0
+        lineno += 1
+        while pos < len(line):
+            if line[pos] in whitespace: # ignore whitespace
+                pass
+            elif line[pos] == ';': # comment
+                break
+            elif line[pos:pos+2] == "'(":
+                pass # the open parenthesis will be handled next iteration
+            elif line[pos] == '(':
+                stack.append(())
+                openlines.append(lineno)
+            elif line[pos] == ')':
+                if len(stack) == 0:
+                    raise error(filename, lineno, 'close parenthesis found when none open')
+                closed = stack[-1]
+                del stack[-1]
+                del openlines[-1]
+                if stack:
+                    stack[-1] += (closed,)
+                else:
+                    yield closed
+            elif line[pos] == '"': # quoted string
+                if not stack:
+                    raise error(filename, lineno,
+                                'string found outside of s-expression')
+                endpos = pos + 1
+                chars = []
+                while endpos < len(line):
+                    if endpos+1 < len(line) and line[endpos] == '\\':
+                        endpos += 1
+                        if line[endpos] == 'n':
+                            chars.append('\n')
+                        elif line[endpos] == 'r':
+                            chars.append('\r')
+                        elif line[endpos] == 't':
+                            chars.append('\t')
+                        else:
+                            chars.append('\\')
+                            chars.append(line[endpos])
+                    elif line[endpos] == '"':
+                        break
+                    else:
+                        chars.append(line[endpos])
+                    endpos += 1
+                if endpos >= len(line):
+                    raise error(filename, lineno, "unclosed quoted string")
+                pos = endpos
+                stack[-1] += (''.join(chars),)
+            else: # symbol/number
+                if not stack:
+                    raise error(filename, lineno,
+                                'identifier found outside of s-expression')
+                endpos = pos
+                while endpos < len(line) and line[endpos] not in nonsymbol:
+                    endpos += 1
+                symbol = line[pos:endpos]
+                pos = max(pos, endpos-1)
+                try: symbol = int(symbol)
+                except ValueError:
+                    try: symbol = float(symbol)
+                    except ValueError: pass
+                stack[-1] += (symbol,)
+            pos += 1
+    if len(stack) != 0:
+        msg = '%d unclosed parentheses found at end of ' \
+              'file (opened on line(s) %s)' % (len(stack),
+                                               ', '.join(map(str, openlines)))
+        raise error(filename, lineno, msg)
+
+class Parser:
+    def __init__(self, filename):
+        """Argument is either a string, a parse tree, or file object"""
+        self.filename = filename
+    def startParsing(self, filename=None):
+        statements = parse(filename or self.filename)
+        for statement in statements:
+            self.handle(statement)
+    def handle(self, tup):
+        cmd = string.translate(tup[0], trans)
+        if hasattr(self, cmd):
+            getattr(self, cmd)(*tup[1:])
+        else:
+            self.unknown(tup)
+    def unknown(self, tup):
+        pass
+
+_testString = """; a scheme file
+(define-func gdk_font_load    ; a comment at end of line
+  GdkFont
+  ((string name)))
+
+(define-boxed GdkEvent
+  gdk_event_copy
+  gdk_event_free
+  "sizeof(GdkEvent)")
+"""
+
+if __name__ == '__main__':
+    import sys
+    if sys.argv[1:]:
+        fp = open(sys.argv[1])
+    else:
+        fp = StringIO(_testString)
+    statements = parse(fp)
+    for s in statements:
+        print `s`