From db918ab21be13a3c1f3c65d3821c06cf12528099 Mon Sep 17 00:00:00 2001

Message-Id: <db918ab21be13a3c1f3c65d3821c06cf12528099.1387369730.git.minovotn@redhat.com>

In-Reply-To: <091eecc4fa42754760dfff393dabcc2b444e9693.1387369730.git.minovotn@redhat.com>

References: <091eecc4fa42754760dfff393dabcc2b444e9693.1387369730.git.minovotn@redhat.com>

From: Markus Armbruster <armbru@redhat.com>

Date: Tue, 10 Dec 2013 15:29:13 +0100

Subject: [PATCH 13/21] qapi.py: Restructure lexer and parser

RH-Author: Markus Armbruster <armbru@redhat.com>

Message-id: <1386689361-30281-11-git-send-email-armbru@redhat.com>

Patchwork-id: 56127

O-Subject: [PATCH 7.0 qemu-kvm 10/18] qapi.py: Restructure lexer and parser

Bugzilla: 997915

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Luiz Capitulino <lcapitulino@redhat.com>

From: Markus Armbruster <armbru@redhat.com>

The parser has a rather unorthodox structure:

    Until EOF:

        Read a section:

            Generator function get_expr() yields one section after the

            other, as a string.  An unindented, non-empty line that

            isn't a comment starts a new section.

        Lexing:

            Split section into a list of tokens (strings), with help

            of generator function tokenize().

        Parsing:

            Parse the first expression from the list of tokens, with

            parse(), throw away any remaining tokens.

            In parse_schema(): record value of an enum, union or

            struct key (if any) in the appropriate global table,

            append expression to the list of expressions.

    Return list of expressions.

Known issues:

(1) Indentation is significant, unlike in real JSON.

(2) Neither lexer nor parser have any idea of source positions.  Error

    reporting is hard, let's go shopping.

(3) The one error we bother to detect, we "report" via raise.

(4) The lexer silently ignores invalid characters.

(5) If everything in a section gets ignored, the parser crashes.

(6) The lexer treats a string containing a structural character exactly

    like the structural character.

(7) Tokens trailing the first expression in a section are silently

    ignored.

(8) The parser accepts any token in place of a colon.

(9) The parser treats comma as optional.

(10) parse() crashes on unexpected EOF.

(11) parse_schema() crashes when a section's expression isn't a JSON

    object.

Replace this piece of original art by a thoroughly unoriginal design.

Takes care of (1), (2), (5), (6) and (7), and lays the groundwork for

addressing the others.  Generated source files remain unchanged.

Signed-off-by: Markus Armbruster <armbru@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Message-id: 1374939721-7876-4-git-send-email-armbru@redhat.com

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

(cherry picked from commit c7a3f25200c8692e969f21c7f2555630ec0d0d30)

---

 scripts/qapi.py                                | 163 +++++++++++++------------

 tests/qapi-schema/indented-expr.out            |   2 +-

 tests/qapi-schema/missing-colon.out            |   4 +-

 tests/qapi-schema/quoted-structural-chars.err  |   1 +

 tests/qapi-schema/quoted-structural-chars.exit |   2 +-

 tests/qapi-schema/quoted-structural-chars.out  |   3 -

 6 files changed, 88 insertions(+), 87 deletions(-)

Signed-off-by: Michal Novotny <minovotn@redhat.com>

---

 scripts/qapi.py                                | 163 +++++++++++++------------

 tests/qapi-schema/indented-expr.out            |   2 +-

 tests/qapi-schema/missing-colon.out            |   4 +-

 tests/qapi-schema/quoted-structural-chars.err  |   1 +

 tests/qapi-schema/quoted-structural-chars.exit |   2 +-

 tests/qapi-schema/quoted-structural-chars.out  |   3 -

 6 files changed, 88 insertions(+), 87 deletions(-)

diff --git a/scripts/qapi.py b/scripts/qapi.py

index 38c808e..58e315b 100644

--- a/scripts/qapi.py

+++ b/scripts/qapi.py

@@ -2,9 +2,11 @@

 # QAPI helper library

 #

 # Copyright IBM, Corp. 2011

+# Copyright (c) 2013 Red Hat Inc.

 #

 # Authors:

 #  Anthony Liguori <aliguori@us.ibm.com>

+#  Markus Armbruster <armbru@redhat.com>

 #

 # This work is licensed under the terms of the GNU GPLv2.

 # See the COPYING.LIB file in the top-level directory.

@@ -32,91 +34,92 @@ builtin_type_qtypes = {

     'uint64':   'QTYPE_QINT',

 }

-def tokenize(data):

-    while len(data):

-        ch = data[0]

-        data = data[1:]

-        if ch in ['{', '}', ':', ',', '[', ']']:

-            yield ch

-        elif ch in ' \n':

-            None

-        elif ch == "'":

-            string = ''

-            esc = False

-            while True:

-                if (data == ''):

-                    raise Exception("Mismatched quotes")

-                ch = data[0]

-                data = data[1:]

-                if esc:

-                    string += ch

-                    esc = False

-                elif ch == "\\":

-                    esc = True

-                elif ch == "'":

-                    break

-                else:

-                    string += ch

-            yield string

-

-def parse(tokens):

-    if tokens[0] == '{':

-        ret = OrderedDict()

-        tokens = tokens[1:]

-        while tokens[0] != '}':

-            key = tokens[0]

-            tokens = tokens[1:]

-

-            tokens = tokens[1:] # :

-

-            value, tokens = parse(tokens)

-

-            if tokens[0] == ',':

-                tokens = tokens[1:]

-

-            ret[key] = value

-        tokens = tokens[1:]

-        return ret, tokens

-    elif tokens[0] == '[':

-        ret = []

-        tokens = tokens[1:]

-        while tokens[0] != ']':

-            value, tokens = parse(tokens)

-            if tokens[0] == ',':

-                tokens = tokens[1:]

-            ret.append(value)

-        tokens = tokens[1:]

-        return ret, tokens

-    else:

-        return tokens[0], tokens[1:]

-

-def evaluate(string):

-    return parse(map(lambda x: x, tokenize(string)))[0]

-

-def get_expr(fp):

-    expr = ''

-

-    for line in fp:

-        if line.startswith('#') or line == '\n':

-            continue

-

-        if line.startswith(' '):

-            expr += line

-        elif expr:

-            yield expr

-            expr = line

+class QAPISchema:

+

+    def __init__(self, fp):

+        self.fp = fp

+        self.src = fp.read()

+        if self.src == '' or self.src[-1] != '\n':

+            self.src += '\n'

+        self.cursor = 0

+        self.exprs = []

+        self.accept()

+

+        while self.tok != None:

+            self.exprs.append(self.get_expr())

+

+    def accept(self):

+        while True:

+            bol = self.cursor == 0 or self.src[self.cursor-1] == '\n'

+            self.tok = self.src[self.cursor]

+            self.cursor += 1

+            self.val = None

+

+            if self.tok == '#' and bol:

+                self.cursor = self.src.find('\n', self.cursor)

+            elif self.tok in ['{', '}', ':', ',', '[', ']']:

+                return

+            elif self.tok == "'":

+                string = ''

+                esc = False

+                while True:

+                    ch = self.src[self.cursor]

+                    self.cursor += 1

+                    if ch == '\n':

+                        raise Exception("Mismatched quotes")

+                    if esc:

+                        string += ch

+                        esc = False

+                    elif ch == "\\":

+                        esc = True

+                    elif ch == "'":

+                        self.val = string

+                        return

+                    else:

+                        string += ch

+            elif self.tok == '\n':

+                if self.cursor == len(self.src):

+                    self.tok = None

+                    return

+

+    def get_members(self):

+        expr = OrderedDict()

+        while self.tok != '}':

+            key = self.val

+            self.accept()

+            self.accept()        # :

+            expr[key] = self.get_expr()

+            if self.tok == ',':

+                self.accept()

+        self.accept()

+        return expr

+

+    def get_values(self):

+        expr = []

+        while self.tok != ']':

+            expr.append(self.get_expr())

+            if self.tok == ',':

+                self.accept()

+        self.accept()

+        return expr

+

+    def get_expr(self):

+        if self.tok == '{':

+            self.accept()

+            expr = self.get_members()

+        elif self.tok == '[':

+            self.accept()

+            expr = self.get_values()

         else:

-            expr += line

-

-    if expr:

-        yield expr

+            expr = self.val

+            self.accept()

+        return expr

 def parse_schema(fp):

+    schema = QAPISchema(fp)

     exprs = []

-    for expr in get_expr(fp):

-        expr_eval = evaluate(expr)

-

+    for expr_eval in schema.exprs:

         if expr_eval.has_key('enum'):

             add_enum(expr_eval['enum'])

         elif expr_eval.has_key('union'):

diff --git a/tests/qapi-schema/indented-expr.out b/tests/qapi-schema/indented-expr.out

index 98ae692..98af89a 100644

--- a/tests/qapi-schema/indented-expr.out

+++ b/tests/qapi-schema/indented-expr.out

@@ -1,3 +1,3 @@

-[OrderedDict([('id', 'eins')])]

+[OrderedDict([('id', 'eins')]), OrderedDict([('id', 'zwei')])]

 []

 []

diff --git a/tests/qapi-schema/missing-colon.out b/tests/qapi-schema/missing-colon.out

index 50f827e..e67068c 100644

--- a/tests/qapi-schema/missing-colon.out

+++ b/tests/qapi-schema/missing-colon.out

@@ -1,3 +1,3 @@

-[OrderedDict([('enum', ','), ('data', ['good', 'bad', 'ugly'])])]

-[',']

+[OrderedDict([('enum', None), ('data', ['good', 'bad', 'ugly'])])]

+[None]

 []

diff --git a/tests/qapi-schema/quoted-structural-chars.err b/tests/qapi-schema/quoted-structural-chars.err

index e69de29..48c849d 100644

--- a/tests/qapi-schema/quoted-structural-chars.err

+++ b/tests/qapi-schema/quoted-structural-chars.err

@@ -0,0 +1 @@

+Crashed: <type 'exceptions.AttributeError'>

diff --git a/tests/qapi-schema/quoted-structural-chars.exit b/tests/qapi-schema/quoted-structural-chars.exit

index 573541a..d00491f 100644

--- a/tests/qapi-schema/quoted-structural-chars.exit

+++ b/tests/qapi-schema/quoted-structural-chars.exit

@@ -1 +1 @@

-0

+1

diff --git a/tests/qapi-schema/quoted-structural-chars.out b/tests/qapi-schema/quoted-structural-chars.out

index 85405be..e69de29 100644

--- a/tests/qapi-schema/quoted-structural-chars.out

+++ b/tests/qapi-schema/quoted-structural-chars.out

@@ -1,3 +0,0 @@

-[OrderedDict([('key1', 'value1'), ('key2', [])])]

-[]

-[]

-- 

1.7.11.7