add hg and python

sys/lib/python/plat-irix5/panelparser.py

@@ -0,0 +1,128 @@
+# Module 'parser'
+#
+# Parse S-expressions output by the Panel Editor
+# (which is written in Scheme so it can't help writing S-expressions).
+#
+# See notes at end of file.
+
+
+whitespace = ' \t\n'
+operators = '()\''
+separators = operators + whitespace + ';' + '"'
+
+
+# Tokenize a string.
+# Return a list of tokens (strings).
+#
+def tokenize_string(s):
+    tokens = []
+    while s:
+        c = s[:1]
+        if c in whitespace:
+            s = s[1:]
+        elif c == ';':
+            s = ''
+        elif c == '"':
+            n = len(s)
+            i = 1
+            while i < n:
+                c = s[i]
+                i = i+1
+                if c == '"': break
+                if c == '\\': i = i+1
+            tokens.append(s[:i])
+            s = s[i:]
+        elif c in operators:
+            tokens.append(c)
+            s = s[1:]
+        else:
+            n = len(s)
+            i = 1
+            while i < n:
+                if s[i] in separators: break
+                i = i+1
+            tokens.append(s[:i])
+            s = s[i:]
+    return tokens
+
+
+# Tokenize a whole file (given as file object, not as file name).
+# Return a list of tokens (strings).
+#
+def tokenize_file(fp):
+    tokens = []
+    while 1:
+        line = fp.readline()
+        if not line: break
+        tokens = tokens + tokenize_string(line)
+    return tokens
+
+
+# Exception raised by parse_exr.
+#
+syntax_error = 'syntax error'
+
+
+# Parse an S-expression.
+# Input is a list of tokens as returned by tokenize_*().
+# Return a pair (expr, tokens)
+# where expr is a list representing the s-expression,
+# and tokens contains the remaining tokens.
+# May raise syntax_error.
+#
+def parse_expr(tokens):
+    if (not tokens) or tokens[0] != '(':
+        raise syntax_error, 'expected "("'
+    tokens = tokens[1:]
+    expr = []
+    while 1:
+        if not tokens:
+            raise syntax_error, 'missing ")"'
+        if tokens[0] == ')':
+            return expr, tokens[1:]
+        elif tokens[0] == '(':
+            subexpr, tokens = parse_expr(tokens)
+            expr.append(subexpr)
+        else:
+            expr.append(tokens[0])
+            tokens = tokens[1:]
+
+
+# Parse a file (given as file object, not as file name).
+# Return a list of parsed S-expressions found at the top level.
+#
+def parse_file(fp):
+    tokens = tokenize_file(fp)
+    exprlist = []
+    while tokens:
+        expr, tokens = parse_expr(tokens)
+        exprlist.append(expr)
+    return exprlist
+
+
+# EXAMPLE:
+#
+# The input
+#       '(hip (hop hur-ray))'
+#
+# passed to tokenize_string() returns the token list
+#       ['(', 'hip', '(', 'hop', 'hur-ray', ')', ')']
+#
+# When this is passed to parse_expr() it returns the expression
+#       ['hip', ['hop', 'hur-ray']]
+# plus an empty token list (because there are no tokens left.
+#
+# When a file containing the example is passed to parse_file() it returns
+# a list whose only element is the output of parse_expr() above:
+#       [['hip', ['hop', 'hur-ray']]]
+
+
+# TOKENIZING:
+#
+# Comments start with semicolon (;) and continue till the end of the line.
+#
+# Tokens are separated by whitespace, except the following characters
+# always form a separate token (outside strings):
+#       ( ) '
+# Strings are enclosed in double quotes (") and backslash (\) is used
+# as escape character in strings.