assimp/scripts/StepImporter/ExpressReader.py

#!/usr/bin/env python3
# -*- Coding: UTF-8 -*-

# ---------------------------------------------------------------------------
# Open Asset Import Library (ASSIMP)
# ---------------------------------------------------------------------------
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# Copyright (c) 2006-2020, ASSIMP Development Team
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#   following disclaimer.
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"""Parse an EXPRESS file and extract basic information on all
entities and data types contained"""

import sys
import re
from collections import OrderedDict

re_match_entity = re.compile(r"""
ENTITY\s+(\w+)\s*                                    # 'ENTITY foo'
.*?                                                  #  skip SUPERTYPE-of
(?:SUBTYPE\s+OF\s+\((\w+)\))?;                       # 'SUBTYPE OF (bar);' or simply ';'
(.*?)                                                # 'a : atype;' (0 or more lines like this)
(?:(?:INVERSE|UNIQUE|WHERE)\s*$.*?)?                 #  skip the INVERSE, UNIQUE, WHERE clauses and everything behind 
END_ENTITY;                                          
""",re.VERBOSE|re.DOTALL|re.MULTILINE) 

re_match_type = re.compile(r"""
TYPE\s+(\w+?)\s*=\s*((?:LIST|SET)\s*\[\d+:[\d?]+\]\s*OF)?(?:\s*UNIQUE)?\s*(\w+)   # TYPE foo = LIST[1:2] of blub
(?:(?<=ENUMERATION)\s*OF\s*\((.*?)\))?
.*?                                                                 #  skip the WHERE clause
END_TYPE;
""",re.VERBOSE|re.DOTALL)

re_match_field = re.compile(r"""
\s+(\w+?)\s*:\s*(OPTIONAL)?\s*((?:LIST|SET)\s*\[\d+:[\d?]+\]\s*OF)?(?:\s*UNIQUE)?\s*(\w+?);
""",re.VERBOSE|re.DOTALL)


class Schema:
    def __init__(self):
        self.entities = OrderedDict()
        self.types = OrderedDict()

class Entity:
    def __init__(self,name,parent,members):
        self.name = name
        self.parent = parent
        self.members = members

class Field:
    def __init__(self,name,type,optional,collection):
        self.name = name
        self.type = type
        self.optional = optional
        self.collection = collection
        self.fullspec = (self.collection+' ' if self.collection else '') + self.type 

class Type:
    def __init__(self,name,aggregate,equals,enums):
        self.name = name
        self.aggregate = aggregate
        self.equals = equals
        self.enums = enums
        

def read(filename, silent=False):
    schema = Schema()
    print( "Try to read EXPRESS schema file" + filename)
    with open(filename,'rt') as inp: 
        contents = inp.read()
        types = re.findall(re_match_type,contents)
        for name,aggregate,equals,enums in types:
            schema.types[name] = Type(name,aggregate,equals,enums)
            
        entities = re.findall(re_match_entity,contents)
        for name,parent,fields_raw in entities:
            print('process entity {0}, parent is {1}'.format(name,parent)) if not silent else None
            fields = re.findall(re_match_field,fields_raw)
            members = [Field(name,type,opt,coll) for name, opt, coll, type in fields]
            print('  got {0} fields'.format(len(members))) if not silent else None
            
            schema.entities[name] = Entity(name,parent,members)
    return schema

if __name__ == "__main__":
    sys.exit(read(sys.argv[1] if len(sys.argv)>1 else 'schema.exp'))