digital_simulator/Parser.py

   1 #
   2 #  Parser.py
   3 #
   4 #
   5 #  Created by Antonio on 2/17/08.
   6 #  Trinary Research Project: Digital logic simulator
   7 #  Upon testing the first phase of this program, correctly defined programs generate
   8 #    no output.
   9 #
  10
  11 from tokenizer import nextToken
  12 from Keyword import *
  13 from Token import *
  14 from Trits import *
  15 from Literal import *
  16 from Identifier import *
  17 from Port import *
  18 from Entity import *
  19
  20 def compareIdentifiers(current, expected, infile):
  21     '''compare current identifier with expected identifier. If they are equal then return
  22        the next token. If they are not then an raise and exeption and exit the program.
  23     '''
  24     if not isinstance(current, Identifier):
  25         raise "Expected '%s', found '%s'" % (expected, current)
  26     else:
  27         print "parsed: %s" % current #for debugging
  28         return nextToken(infile)
  29
  30 def compareTokens(current, expected, infile):
  31     '''compare token current with expected token.  If they are equal then return the next
  32     token, if they are not then an raise exeption and exit program.
  33     '''
  34     if not isinstance(current, Token) or  current.name != expected.name:
  35         raise "Expected '%s', found '%s'" % (expected, current)
  36     else:
  37         print "parsed: %s" % current #for debugging
  38         return nextToken(infile)
  39
  40 def compareKeywords(current, expected, infile):
  41     '''compare current keyword with expected keyword. If they are equal then return
  42        the next token. If they are not then an raise and exeption and exit the program.
  43     '''
  44     if not isinstance(current, Keyword) or  current.name != expected.name:
  45         raise "Expected '%s', found '%s'" % (expected, current)
  46     else:
  47         print "parsed: %s" % current #for debugging
  48         return nextToken(infile)
  49
  50 def printError(current, expected):
  51     '''Function prints an error message and raises an exeption
  52     '''
  53     raise "Expected '%s', found '%s'\n" % (expected, current)
  54
  55 def parse_datatype(current, infile):
  56     '''parse the datatype and return Trit object that identifies the datatype
  57     '''
  58     if isinstance (current, Keyword):
  59         if current.name == "trit":
  60             return (nextToken(infile), "trit", 0)
  61         next =  compareKeywords(current, Keyword("trit_vector"), infile)
  62
  63         valueOne = compareTokens(next, Token("("), infile)
  64
  65         if not isinstance(valueOne, Literal):
  66             printError(valueOne, Literal("integer"))
  67         elif valueOne.value <= 0:
  68             printError(valueOne, Literal("greater than zero"))
  69         valueTwo = nextToken(infile)
  70
  71         length = valueOne.value + 1
  72
  73         valueThree = compareTokens(valueTwo, Keyword("downto"), infile)
  74         if not isinstance(valueThree, Literal):
  75             printError(valueThree, Literal("integer"))
  76         elif valueThree.value != 0:
  77             printError(valueThree, Literal(0))
  78         valueFour = nextToken(infile)
  79
  80         valueFive = compareTokens(valueFour, Token(")"), infile)
  81
  82         # construct datatype object for trit_vector and return it
  83         # along with the next token
  84         return (valueFive, "trit_vector", length)
  85
  86     printError(current, Keyword("trit|trit_vector"))
  87
  88 def parse_flow(current, infile):
  89     '''identify the direction of the flow of the port
  90     '''
  91     if isinstance(current, Keyword):
  92         if current.name == "in":
  93             return (nextToken(infile), "in")
  94         elif current.name == "out":
  95             return (nextToken(infile), "out")
  96         elif current.name == "inout":
  97             return (nextToken(infile), "inout")
  98
  99     printError(current, Keyword("in|out|inout"))
 100
 101 def parse_port(next, infile, entity):
 102     '''parse the port and return a 'port' object
 103     '''
 104     names = []
 105
 106     while 1:
 107         cont = compareIdentifiers(next, Identifier(" "), infile)
 108         names.append(next.name)
 109         if not isinstance(cont, Token) or cont.name != ",":
 110             break
 111         else:
 112             next = nextToken(infile)
 113
 114     valueOne = compareTokens(cont, Token(":"), infile)
 115     (valueTwo, flow) = parse_flow(valueOne, infile)
 116     (valueThree, type, length) = parse_datatype(valueTwo, infile)
 117
 118     # store derived port information into Entity
 119     for i in names:
 120         if flow == "in":
 121             entity.IN.append(Port.Port(i, Port.IN, type, length))
 122         elif flow == "out":
 123             entity.OUT.append(Port.Port(i, Port.OUT, type, length))
 124         else:
 125             entity.INOUT.append(Port.Port(i, Port.INOUT, type, length))
 126
 127     # recurse if there are more ports defined
 128     if isinstance (valueThree, Token) and valueThree.name == ";":
 129         return parse_port(nextToken(infile), infile, entity)
 130     else:
 131         return (valueThree, entity)
 132
 133 def parse_entitytype(current, infile, entity):
 134     '''parse the type of the entity
 135     '''
 136     value1 = compareKeywords(current, Keyword("port"), infile)
 137     value2 = compareTokens(value1, Token("("), infile)
 138     (value3, rtn) = parse_port(value2, infile, entity)
 139     value4 = compareTokens(value3, Token(")"), infile)
 140
 141     return (value4, entity);
 142
 143 def parse_entity(current, infile):
 144     '''Parse the entity'''
 145     value1 = compareKeywords(current, Keyword("entity"), infile)
 146     value2 = compareIdentifiers(value1, Identifier(" "), infile)
 147
 148     # create entity object
 149     entity = Entity(value1.name, [])
 150
 151     value3 = compareKeywords(value2, Keyword("is"), infile)
 152     (value4, rtn) = parse_entitytype(value3, infile, entity)
 153     value5 = compareTokens(value4, Token(";"), infile)
 154     value6 = compareKeywords(value5, Keyword("end"), infile)
 155     value7 = compareIdentifiers(value6, Identifier(" "), infile)
 156
 157     # identifier names must match
 158     if value6.name != value1.name:
 159         printError(value6, value1)
 160
 161     value8 = compareTokens(value7, Token(";"), infile)
 162
 163     # return Entity object
 164     return (value8, entity)
 165
 166 def parse_architecture(current, infile):
 167     '''Parse the archtecture component.'''
 168     value1 = compareKeywords(current, Keyword("architecture"), infile)
 169     value2 = compareKeywords(value1, Keyword("dataflow"), infile)
 170     value3 = compareKeywords(value2, Keyword("of"), infile)
 171     value4 = compareIdentifiers(value3, Identifier(" "), infile)
 172
 173     archi = Architecture(value3.name)
 174
 175     value5 = compareKeywords(value4, Keyword("is"), infile)
 176     value6 = compareKeywords(value5, Keyword("begin"), infile)
 177     value7 = compareKeywords(value6, Keyword("end"), infile)
 178     value8 = compareKeywords(value7, Keyword("dataflow"), infile)
 179     value9 = compareTokens(value8, Token(";"), infile)
 180
 181     return (value9, archi)
 182
 183 def parse_program(current, infile):
 184     '''parse the individual components of the program'''
 185     while isinstance(current, Keyword):
 186         if current.name == "entity":
 187             (current, entity) = parse_entity(current, infile)
 188             print "Parsed Entity: %s" % entity
 189         elif current.name == "architecture":
 190             (current, architecture) = parse_architecture(current, infile)
 191             print "Parsed Architecture: %s" % architecture
 192
 193 def Parser(filename):
 194     '''Parse a file into components.
 195        Arguments (1): filename of the file to parse.
 196     '''
 197     infile = file(filename, "r")
 198     parse_program(nextToken(infile), infile)
 199
 200 if __name__ == "__main__":
 201     Parser("testParser");
 202