[Qemu-devel] [PATCH 18/22] qidl: add lexer library (based on QC parser)

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Adds an abstract Lexer class to handle tokenizer via a
peek/pop/peekline/popline interface, along with an implementation for C
based on the lexer from qc.git

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 scripts/lexer.py |  306 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 306 insertions(+)
 create mode 100644 scripts/lexer.py

diff --git a/scripts/lexer.py b/scripts/lexer.py
new file mode 100644
index 0000000..e740e5c
--- /dev/null
+++ b/scripts/lexer.py
@@ -0,0 +1,306 @@
+#
+# QEMU Lexer Library
+#
+# Copyright IBM, Corp. 2012
+#
+# Authors:
+#  Anthony Liguori <aliguori@us.ibm.com>
+#  Michael Roth    <mdroth@linux.vnet.ibm.com>
+#
+# This work is licensed under the terms of the GNU GPLv2.
+# See the COPYING file in the top-level directory.
+#
+# The lexer code is based off of:
+#   http://www.lysator.liu.se/c/ANSI-C-grammar-l.html
+
+class Input(object):
+    def __init__(self, fp):
+        self.fp = fp
+        self.line = None
+        self.offset = 0
+        self.is_eof = False
+        self.__fill_buf()
+
+    def __fill_buf(self):
+        if not self.line and not self.is_eof:
+            self.line = self.fp.readline()
+            if not self.line:
+                self.is_eof = True
+
+    def peek(self):
+        if self.is_eof:
+            return ""
+        return self.line[self.offset]
+
+    def pop(self):
+        if self.is_eof:
+            return ""
+        ch = self.line[self.offset]
+        self.offset += 1
+        if self.offset == len(self.line):
+            self.offset = 0
+            self.line = None
+            self.__fill_buf()
+        return ch
+
+    def peek_line(self):
+        return self.line
+
+    def pop_line(self):
+        line = self.line
+        self.line = None
+        self.offset = 0
+        self.__fill_buf()
+        return line
+
+    def eof(self):
+        return self.is_eof
+
+class Lexer(object):
+    def __init__(self, input, ignored_types=[]):
+        self.input = input
+        self.ignored_types = ignored_types
+        self.current_type = None
+        self.current_value = None
+
+    def get_token(self):
+        raise NotImplemented("derived classes must implement this method")
+
+    def __ensure_token(self):
+        while self.current_type == None and not self.input.eof():
+            t, v = self.get_token()
+            if t not in self.ignored_types:
+                self.current_type = t
+                self.current_value = v
+
+    def peek(self):
+        self.__ensure_token()
+        return self.current_value
+
+    def peek_line(self):
+        self.__ensure_token()
+        return self.input.peek_line()
+
+    def peek_type(self):
+        self.__ensure_token()
+        return self.current_type
+
+    def pop(self):
+        self.__ensure_token()
+        v = self.current_value
+        self.current_type = None
+        self.current_value = None
+        return v
+
+    def pop_line(self):
+        self.__ensure_token()
+        self.current_type = None
+        self.current_value = None
+        return self.input.pop_line()
+
+    def pop_expected(self, type_expected=None, value_expected=None):
+        self.__ensure_token()
+        if self.current_type != type_expected:
+            raise Exception("expected '%s', got %s %s" %
+                (type_expected, self.current_type, self.current_value))
+        if value_expected != None:
+            if self.current_value != value_expected:
+                raise Exception("expected '%s', got %s" %
+                    (value_expected, self.current_value))
+        return self.pop()
+    
+    def check_token(self, type_expected, value_expected=None):
+        self.__ensure_token()
+        if self.current_type != type_expected:
+            return False
+        if value_expected != None:
+            if self.current_value != value_expected:
+                return False
+        return True
+
+    def eof(self):
+        self.__ensure_token()
+        return self.current_type == None
+
+def in_range(ch, start, end):
+    if ch >= start and ch <= end:
+        return True
+    return False
+
+# D			[0-9]
+# L			[a-zA-Z_]
+# H			[a-fA-F0-9]
+# E			[Ee][+-]?{D}+
+# FS			(f|F|l|L)
+# IS			(u|U|l|L)*
+
+def is_D(ch):
+    return in_range(ch, '0', '9')
+
+def is_L(ch):
+    return in_range(ch, 'a', 'z') or in_range(ch, 'A', 'Z') or ch == '_'
+
+def is_H(ch):
+    return in_range(ch, 'a', 'f') or in_range(ch, 'A', 'F') or is_D(ch)
+
+def is_FS(ch):
+    return ch in 'fFlL'
+
+def is_IS(ch):
+    return ch in 'uUlL'
+
+class CLexer(Lexer):
+    def __init__(self, input, ignored_types=[]):
+        super(CLexer, self).__init__(input, ignored_types)
+
+    # used internally, external users should use
+    # CLexer.peek()/peek_type()/pop() instead
+    def get_token(self):
+        token = ''
+        while not self.input.eof():
+            ch = self.input.peek()
+
+            if is_L(ch):
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                while is_L(ch) or is_D(ch):
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                if token in [ 'auto', 'break', 'case', 'const', 'continue',
+                               'default', 'do', 'else', 'enum', 'extern',
+                               'for', 'goto', 'if', 'register', 'return',
+                               'signed', 'sizeof',
+                               'static', 'struct', 'typedef', 'union',
+                               'unsigned', 'volatile', 'while' ]:
+                    return (token, token)
+                else:
+                    return ('symbol', token)
+            elif ch == "'":
+                token += ch
+                self.input.pop()
+                
+                ch = self.input.peek()
+                if ch == '\\':
+                    token += ch
+                    self.input.pop()
+                    token += self.input.pop()
+                else:
+                    token += ch
+                token += self.input.pop()
+                return ('literal', token)
+            elif ch == '"':
+                token += ch
+                self.input.pop()
+
+                ch = self.input.peek()
+                while ch not in ['', '"']:
+                    token += ch
+                    self.input.pop()
+                    if ch == '\\':
+                        token += self.input.pop()
+                    ch = self.input.peek()
+                token += ch
+                self.input.pop()
+                return ('literal', token)
+            elif ch in '.><+-*/%&^|!;{},:=()[]~?':
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                tmp_token = token + ch
+                if tmp_token in ['<:']:
+                    return ('operator', '[')
+                elif tmp_token in [':>']:
+                    return ('operator', ']')
+                elif tmp_token in ['<%']:
+                    return ('operator', '{')
+                elif tmp_token in ['%>']:
+                    return ('operator', '}')
+                elif tmp_token == '//':
+                    token = tmp_token
+                    ch = self.input.peek()
+                    while ch != '\n' and ch != '':
+                        token += ch
+                        self.input.pop()
+                        ch = self.input.peek()
+                    return ('comment', token)
+                elif tmp_token == '/*':
+                    token = tmp_token
+                    self.input.pop()
+
+                    ch = self.input.peek()
+                    while True:
+                        while ch != '*':
+                            token += ch
+                            self.input.pop()
+                            ch = self.input.peek()
+                        token += ch
+                        self.input.pop()
+                        ch = self.input.peek()
+                        if ch == '/':
+                            token += ch
+                            self.input.pop()
+                            break
+                    return ('comment', token)
+                elif tmp_token in [ '+=', '-=', '*=', '/=', '%=', '&=', '^=',
+                                    '|=', '>>', '<<', '++', '--', '->', '&&',
+                                    '||', '<=', '>=', '==', '!=' ]:
+                    return ('operator', tmp_token)
+                else:
+                    return ('operator', token)
+            elif ch == '0':
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                if ch in 'xX':
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                    while is_H(ch):
+                        token += ch
+                        self.input.pop()
+                        ch = self.input.peek()
+                    while is_IS(ch):
+                        token += ch
+                        self.input.pop()
+                        ch = self.input.peek()
+                elif is_D(ch):
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                    while is_D(ch):
+                        token += ch
+                        self.input.pop()
+                        ch = self.input.peek()
+                return ('literal', token)
+            elif is_D(ch):
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                while is_D(ch):
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                return ('literal', token)
+            elif ch in ' \t\v\n\f':
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                while len(ch) and ch in ' \t\v\n\f':
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                return ('whitespace', token)
+            elif ch in '#':
+                token += ch
+                self.input.pop()
+                ch = self.input.peek()
+                while len(ch) and ch != '\n':
+                    token += ch
+                    self.input.pop()
+                    ch = self.input.peek()
+                return ('directive', token)
+            else:
+                return ('unknown', ch)
+        return (None, None)
-- 
1.7.9.5