BPL BPL - 2 months ago 14
Python Question

glsl parser using pyparsing giving AttributeErrors

I'm trying to update this glsl-parser which uses an old pyparsing version and python2.x to python3.x & the newest pyparsing version (2.1.9 atm).

I don't know which pyparsing version was using the original source code but it must be quite old because is still using

keepOriginalText
helper method, after reading pyparsing news I've seen this comment
Removed keepOriginalText helper method, which was deprecated ages ago. Superceded by originalTextFor.


Anyway, here's the first attempt of the port using python3.5.1 & pyparsing==2.1.9:

# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright (c) 2014, Nicolas P. Rougier
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
import pyparsing

keywords = ("attribute const uniform varying break continue do for while"
"if else"
"in out inout"
"float int void bool true false"
"lowp mediump highp precision invariant"
"discard return"
"mat2 mat3 mat4"
"vec2 vec3 vec4 ivec2 ivec3 ivec4 bvec2 bvec3 bvec4 sampler2D samplerCube"
"struct")
reserved = ("asm"
"class union enum typedef template this packed"
"goto switch default"
"inline noinline volatile public static extern external"
"interface flat long short double half fixed unsigned superp"
"input output"
"hvec2 hvec3 hvec4 dvec2 dvec3 dvec4 fvec2 fvec3 fvec4 sampler1D sampler3D"
"sampler1DShadow sampler2DShadow"
"sampler2DRect sampler3DRect sampler2DRectShadow"
"sizeof cast"
"namespace using")
precision = "lowp mediump high"
storage = "const uniform attribute varying"


# Tokens
# ----------------------------------
LPAREN = pyparsing.Literal("(").suppress()
RPAREN = pyparsing.Literal(")").suppress()
LBRACK = pyparsing.Literal("[").suppress()
RBRACK = pyparsing.Literal("]").suppress()
LBRACE = pyparsing.Literal("{").suppress()
RBRACE = pyparsing.Literal("}").suppress()
IDENTIFIER = pyparsing.Word(pyparsing.alphas + '_', pyparsing.alphanums + '_')
TYPE = pyparsing.Word(pyparsing.alphas + '_', pyparsing.alphanums + "_")
END = pyparsing.Literal(";").suppress()
INT = pyparsing.Word(pyparsing.nums)
FLOAT = pyparsing.Regex(
'[+-]?(((\d+\.\d*)|(\d*\.\d+))([eE][-+]?\d+)?)|(\d*[eE][+-]?\d+)')
STORAGE = pyparsing.Regex('|'.join(storage.split(' ')))
PRECISION = pyparsing.Regex('|'.join(precision.split(' ')))
STRUCT = pyparsing.Literal("struct").suppress()


# ------------------------
def get_prototypes(code):
"""
Get all function declarations

Code example
------------

mediump vec3 function_1(vec4);
vec3 function_2(float a, float b);
"""

PARAMETER = pyparsing.Group(pyparsing.Optional(PRECISION).setResultsName("precision") +
TYPE.setResultsName("type") +
pyparsing.Optional(IDENTIFIER).setResultsName("name"))
PARAMETERS = pyparsing.delimitedList(PARAMETER).setResultsName(
"arg", listAllMatches=True)
PROTOTYPE = (pyparsing.Optional(PRECISION).setResultsName("precision") +
TYPE.setResultsName("type") +
IDENTIFIER.setResultsName("name") +
LPAREN + pyparsing.Optional(PARAMETERS).setResultsName("args") + RPAREN +
END)
PROTOTYPE.ignore(pyparsing.cStyleComment)

for (token, start, end) in PROTOTYPE.scanString(code):
print(token.precision, token.type, token.name, '(',)
for arg in token.args:
print(arg.precision, arg.type, arg.name, ',',)
print(')')


# ------------------------
def get_functions(code):
"""
Get all function definitions

Code example
------------

mediump vec3 compute_normal(vec4);
"""

PARAMETER = pyparsing.Group(pyparsing.Optional(PRECISION).setResultsName("precision") +
TYPE.setResultsName("type") +
pyparsing.Optional(IDENTIFIER).setResultsName("name"))
PARAMETERS = pyparsing.delimitedList(PARAMETER).setResultsName(
"arg", listAllMatches=True)
FUNCTION = (pyparsing.Optional(PRECISION).setResultsName("precision") +
TYPE.setResultsName("type") +
IDENTIFIER.setResultsName("name") +
LPAREN + pyparsing.Optional(PARAMETERS).setResultsName("args") + RPAREN +
pyparsing.nestedExpr("{", "}").setParseAction(pyparsing.originalTextFor).setResultsName("code"))
FUNCTION.ignore(pyparsing.cStyleComment)

for (token, start, end) in FUNCTION.scanString(code):
print(token.precision, token.type, token.name, '(',)
for arg in token.args:
print(arg.precision, arg.type, arg.name, ',',)
print(') { ... }')

# print token.code
# print code[start:end]


# ------------------------
def get_version(code):
"""
Get shader version (if specified)

Code example
------------

#version 120
"""

VERSION = (
pyparsing.Literal("#") + pyparsing.Keyword("version")).suppress() + INT
for (token, start, end) in VERSION.scanString(code):
version = token[0]
# print code[start:end]
return version

# ------------------------


def get_declarations(code):
"""
Get all declarations prefixed with a storage qualifier.

Code example
------------

uniform lowp vec4 fg_color = vec4(1),
bg_color = vec4(vec3(0),1);
"""

# Callable expression
EXPRESSION = pyparsing.Forward()
ARG = pyparsing.Group(EXPRESSION) | IDENTIFIER | FLOAT | INT
ARGS = pyparsing.delimitedList(ARG)
EXPRESSION << IDENTIFIER + \
pyparsing.Group(LPAREN + pyparsing.Optional(ARGS) + RPAREN)

# Value
VALUE = (EXPRESSION | pyparsing.Word(pyparsing.alphanums + "_()+-/*")
).setParseAction(pyparsing.originalTextFor)

# Single declaration
VARIABLE = (IDENTIFIER.setResultsName("name") +
pyparsing.Optional(LBRACK +
(INT | IDENTIFIER).setResultsName("size")
+ RBRACK) +
pyparsing.Optional(pyparsing.Literal("=").suppress() + VALUE.setResultsName("value")))

# Several declarations at once
DECLARATION = (STORAGE.setResultsName("storage") +
pyparsing.Optional(PRECISION).setResultsName("precision") +
TYPE.setResultsName("type") +
pyparsing.delimitedList(VARIABLE.setResultsName("variable", listAllMatches=True)) +
END)
DECLARATION.ignore(pyparsing.cStyleComment)

for (tokens, start, end) in DECLARATION.scanString(code):
for token in tokens.variable:
print(tokens.storage, tokens.precision, tokens.type,)
print(token.name, token.size)


# ------------------------
def get_definitions(code):
"""
Get all structure definitions and associated declarations.

Code example
------------

uniform struct Light {
vec4 position;
vec3 color;
} light0, light1;
"""

# Single declaration
DECLARATION = pyparsing.Group(IDENTIFIER.setResultsName("name") +
pyparsing.Optional(LBRACK +
(INT | IDENTIFIER).setResultsName("size") +
RBRACK))
# Several declarations at once
DECLARATIONS = (pyparsing.Optional(PRECISION) +
TYPE +
pyparsing.delimitedList(DECLARATION) +
END)

# Definition + declarations
DEFINITION = (STRUCT +
IDENTIFIER.setResultsName("name") +
LBRACE + pyparsing.OneOrMore(DECLARATIONS).setResultsName('content') + RBRACE +
pyparsing.Optional(pyparsing.delimitedList(DECLARATION.setResultsName("declarations", listAllMatches=True))) +
END)
DEFINITION.ignore(pyparsing.cStyleComment)

for (tokens, start, end) in DEFINITION.scanString(code):
for token in tokens.declarations:
print(tokens.name, token.name)
# print tokens.content


# ----------------
def resolve(code):
"""
Expand const and preprocessor definitions in order to get constant values.

Return the transformed code
"""

constants = {}

DEFINITION = (pyparsing.Literal("#") + pyparsing.Literal("define") +
IDENTIFIER.setResultsName("name") +
pyparsing.restOfLine.setResultsName("value"))

VALUE = pyparsing.Word(pyparsing.alphanums + "_()+-/*")
DECLARATION = (pyparsing.Literal("const") +
TYPE.setResultsName("type") +
IDENTIFIER.setResultsName("name") +
pyparsing.Literal("=") +
VALUE.setResultsName("value") +
pyparsing.Literal(";"))
REFERENCE = pyparsing.Forward()

def process_definition(s, l, t):
value = REFERENCE.transformString(t.value)
constants[t.name] = value
REFERENCE << pyparsing.MatchFirst(
map(pyparsing.Keyword, constants.keys()))
return "#define " + t.name + " " + value

def process_declaration(s, l, t):
value = REFERENCE.transformString(t.value)
constants[t.name] = value
REFERENCE << pyparsing.MatchFirst(
map(pyparsing.Keyword, constants.keys()))
return "const " + t.type + " " + t.name + "=" + value + ";"

def process_reference(s, l, t):
return constants[t[0]]

REFERENCE.setParseAction(process_reference)
DEFINITION.setParseAction(process_definition)
DECLARATION.setParseAction(process_declaration)
EXPANDER = REFERENCE | DEFINITION | DECLARATION

code = EXPANDER.transformString(code)
for key, val in constants.items():
constants[key] = eval(val)

return code, constants


# -----------------------------------------------------------------------------
if __name__ == '__main__':

code = """
#version 120

#define A (1)
const int B=(A+2);
#define C (B+3)
const int D=C+4;

uniform float array[D];

struct Point {
vec4 position;
float size;
};

uniform struct Light {
vec4 position;
vec3 color;
} light0, light1;

const float PI = 3.14159265358979323846264;
const float SQRT_2 = 1.4142135623730951;

uniform vec4 fg_color = vec4(1),
bg_color = vec4(vec3(0),1);

mediump vec3 compute_normal(vec4 position, vec3 orientation);
vec3 /* */ compute_light(vec4, vec3, float intensity)
{
vec3 hello;
vec3 hello;
}

"""
code, _ = resolve(code)
print("GLSL version: %s\n" % get_version(code))

get_definitions(code)
get_declarations(code)
get_prototypes(code)
get_functions(code)

# code = """
# #if A
# #if B
# #if C
# #endif
# #endif
# #endif
# """

# IF = (pyparsing.Literal('#') + (pyparsing.Keyword('if') | pyparsing.Keyword('ifdef') | pyparsing.Keyword('ifndef')))
# ENDIF = (pyparsing.Literal('#') + pyparsing.Keyword('endif'))
# MACRO = (IF + pyparsing.restOfLine() +
# SkipTo(ENDIF, include=True)).setParseAction(pyparsing.originalTextFor)
# for (tokens, start, end) in MACRO.scanString(code):
# print tokens


When you try running the above mcve code you'll get:

GLSL version: 120

('Light', 'light0')
('Light', 'light1')
d:\virtual_envs\py2711\lib\site-packages\pyparsing.py:3536: SyntaxWarning: Cannot combine element of type <type 'int'> with ParserElement
matchExpr = locMarker("_original_start") + expr + endlocMarker("_original_end")
d:\virtual_envs\py2711\lib\site-packages\pyparsing.py:3536: SyntaxWarning: Cannot combine element of type <type 'NoneType'> with ParserElement
matchExpr = locMarker("_original_start") + expr + endlocMarker("_original_end")
Traceback (most recent call last):
File "D:\sources\personal\python\pyqt\pyshaders\gui\glsl-parser.py", line 311, in <module>
get_declarations(code)
File "D:\sources\personal\python\pyqt\pyshaders\gui\glsl-parser.py", line 173, in get_declarations
for (tokens, start, end) in DECLARATION.scanString(code):
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1258, in scanString
nextLoc,tokens = parseFn( instring, preloc, callPreParse=False )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1084, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 2576, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1084, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 2576, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1084, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 3038, in parseImpl
loc, tokens = self.expr._parse( instring, loc, doActions, callPreParse=False )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1084, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 2576, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 1110, in _parseNoCache
tokens = fn( instring, tokensStart, retTokens )
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 831, in wrapper
ret = func(*args[limit[0]:])
File "d:\virtual_envs\py2711\lib\site-packages\pyparsing.py", line 3542, in originalTextFor
matchExpr.setParseAction(extractText)
AttributeError: 'NoneType' object has no attribute 'setParseAction'


I'm still in the process of learning pyparsing, what's the problem here?

Answer

originalTextFor is not a parse action, but a helper method that attaches a parse action to a defined expression. In your example it is used in two places:

# Value
VALUE = (EXPRESSION | pyparsing.Word(pyparsing.alphanums + "_()+-/*")
         ).setParseAction(pyparsing.originalTextFor)

FUNCTION = (pyparsing.Optional(PRECISION).setResultsName("precision") +
            TYPE.setResultsName("type") +
            IDENTIFIER.setResultsName("name") +
            LPAREN + pyparsing.Optional(PARAMETERS).setResultsName("args") + RPAREN +
            pyparsing.nestedExpr("{", "}").setParseAction(pyparsing.originalTextFor).setResultsName("code"))

change these to:

# Value
VALUE = pyparsing.originalTextFor(EXPRESSION |
                                  pyparsing.Word(pyparsing.alphanums + "_()+-/*"))

FUNCTION = (pyparsing.Optional(PRECISION).setResultsName("precision") +
            TYPE.setResultsName("type") +
            IDENTIFIER.setResultsName("name") +
            LPAREN + pyparsing.Optional(PARAMETERS).setResultsName("args") + RPAREN +
            pyparsing.originalTextFor(pyparsing.nestedExpr("{", "}")).setResultsName("code"))

You might find that the more recent pyparsing form of setResultsName to be a little cleaner-looking, but the old form still works fine:

FUNCTION = (pyparsing.Optional(PRECISION)("precision") +
            TYPE("type") +
            IDENTIFIER("name") +
            LPAREN + pyparsing.Optional(PARAMETERS)("args") + RPAREN +
            pyparsing.originalTextFor(pyparsing.nestedExpr("{", "}"))("code"))

If you make this change, those places that use listAllMatches are handled by adding a '*' to the name argument:

pyparsing.delimitedList(VARIABLE("variable*"))
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