diff options
Diffstat (limited to 'trunk/src/examples/fourFn.py')
| -rw-r--r-- | trunk/src/examples/fourFn.py | 192 |
1 files changed, 0 insertions, 192 deletions
diff --git a/trunk/src/examples/fourFn.py b/trunk/src/examples/fourFn.py deleted file mode 100644 index 75f3909..0000000 --- a/trunk/src/examples/fourFn.py +++ /dev/null @@ -1,192 +0,0 @@ -# fourFn.py
-#
-# Demonstration of the pyparsing module, implementing a simple 4-function expression parser,
-# with support for scientific notation, and symbols for e and pi.
-# Extended to add exponentiation and simple built-in functions.
-# Extended test cases, simplified pushFirst method.
-# Removed unnecessary expr.suppress() call (thanks Nathaniel Peterson!), and added Group
-# Changed fnumber to use a Regex, which is now the preferred method
-#
-# Copyright 2003-2009 by Paul McGuire
-#
-from pyparsing import Literal,CaselessLiteral,Word,Group,Optional,\
- ZeroOrMore,Forward,nums,alphas,alphanums,Regex,ParseException,\
- CaselessKeyword, Suppress
-import math
-import operator
-
-exprStack = []
-
-def pushFirst( strg, loc, toks ):
- exprStack.append( toks[0] )
-def pushUMinus( strg, loc, toks ):
- for t in toks:
- if t == '-':
- exprStack.append( 'unary -' )
- #~ exprStack.append( '-1' )
- #~ exprStack.append( '*' )
- else:
- break
-
-bnf = None
-def BNF():
- """
- expop :: '^'
- multop :: '*' | '/'
- addop :: '+' | '-'
- integer :: ['+' | '-'] '0'..'9'+
- atom :: PI | E | real | fn '(' expr ')' | '(' expr ')'
- factor :: atom [ expop factor ]*
- term :: factor [ multop factor ]*
- expr :: term [ addop term ]*
- """
- global bnf
- if not bnf:
- point = Literal( "." )
- # use CaselessKeyword for e and pi, to avoid accidentally matching
- # functions that start with 'e' or 'pi' (such as 'exp'); Keyword
- # and CaselessKeyword only match whole words
- e = CaselessKeyword( "E" )
- pi = CaselessKeyword( "PI" )
- #~ fnumber = Combine( Word( "+-"+nums, nums ) +
- #~ Optional( point + Optional( Word( nums ) ) ) +
- #~ Optional( e + Word( "+-"+nums, nums ) ) )
- fnumber = Regex(r"[+-]?\d+(?:\.\d*)?(?:[eE][+-]?\d+)?")
- ident = Word(alphas, alphanums+"_$")
-
- plus, minus, mult, div = map(Literal, "+-*/")
- lpar, rpar = map(Suppress, "()")
- addop = plus | minus
- multop = mult | div
- expop = Literal( "^" )
-
- expr = Forward()
- atom = ((0,None)*minus + ( pi | e | fnumber | ident + lpar + expr + rpar | ident ).setParseAction( pushFirst ) |
- Group( lpar + expr + rpar )).setParseAction(pushUMinus)
-
- # by defining exponentiation as "atom [ ^ factor ]..." instead of "atom [ ^ atom ]...", we get right-to-left exponents, instead of left-to-righ
- # that is, 2^3^2 = 2^(3^2), not (2^3)^2.
- factor = Forward()
- factor << atom + ZeroOrMore( ( expop + factor ).setParseAction( pushFirst ) )
-
- term = factor + ZeroOrMore( ( multop + factor ).setParseAction( pushFirst ) )
- expr << term + ZeroOrMore( ( addop + term ).setParseAction( pushFirst ) )
- bnf = expr
- return bnf
-
-# map operator symbols to corresponding arithmetic operations
-epsilon = 1e-12
-opn = { "+" : operator.add,
- "-" : operator.sub,
- "*" : operator.mul,
- "/" : operator.truediv,
- "^" : operator.pow }
-fn = { "sin" : math.sin,
- "cos" : math.cos,
- "tan" : math.tan,
- "exp" : math.exp,
- "abs" : abs,
- "trunc" : lambda a: int(a),
- "round" : round,
- "sgn" : lambda a: (a > epsilon) - (a < -epsilon) }
-def evaluateStack( s ):
- op = s.pop()
- if op == 'unary -':
- return -evaluateStack( s )
- if op in "+-*/^":
- op2 = evaluateStack( s )
- op1 = evaluateStack( s )
- return opn[op]( op1, op2 )
- elif op == "PI":
- return math.pi # 3.1415926535
- elif op == "E":
- return math.e # 2.718281828
- elif op in fn:
- return fn[op]( evaluateStack( s ) )
- elif op[0].isalpha():
- raise Exception("invalid identifier '%s'" % op)
- else:
- return float( op )
-
-if __name__ == "__main__":
-
- def test( s, expVal ):
- global exprStack
- exprStack[:] = []
- try:
- results = BNF().parseString( s, parseAll=True )
- val = evaluateStack( exprStack[:] )
- except ParseException as e:
- print(s, "failed parse:", str(pe))
- except Exception as e:
- print(s, "failed eval:", str(e))
- else:
- if val == expVal:
- print(s, "=", val, results, "=>", exprStack)
- else:
- print(s+"!!!", val, "!=", expVal, results, "=>", exprStack)
-
- test( "9", 9 )
- test( "-9", -9 )
- test( "--9", 9 )
- test( "-E", -math.e )
- test( "9 + 3 + 6", 9 + 3 + 6 )
- test( "9 + 3 / 11", 9 + 3.0 / 11 )
- test( "(9 + 3)", (9 + 3) )
- test( "(9+3) / 11", (9+3.0) / 11 )
- test( "9 - 12 - 6", 9 - 12 - 6 )
- test( "9 - (12 - 6)", 9 - (12 - 6) )
- test( "2*3.14159", 2*3.14159 )
- test( "3.1415926535*3.1415926535 / 10", 3.1415926535*3.1415926535 / 10 )
- test( "PI * PI / 10", math.pi * math.pi / 10 )
- test( "PI*PI/10", math.pi*math.pi/10 )
- test( "PI^2", math.pi**2 )
- test( "round(PI^2)", round(math.pi**2) )
- test( "6.02E23 * 8.048", 6.02E23 * 8.048 )
- test( "e / 3", math.e / 3 )
- test( "sin(PI/2)", math.sin(math.pi/2) )
- test( "trunc(E)", int(math.e) )
- test( "trunc(-E)", int(-math.e) )
- test( "round(E)", round(math.e) )
- test( "round(-E)", round(-math.e) )
- test( "E^PI", math.e**math.pi )
- test( "exp(0)", 1 )
- test( "exp(1)", math.e )
- test( "2^3^2", 2**3**2 )
- test( "2^3+2", 2**3+2 )
- test( "2^3+5", 2**3+5 )
- test( "2^9", 2**9 )
- test( "sgn(-2)", -1 )
- test( "sgn(0)", 0 )
- test( "foo(0.1)", None )
- test( "sgn(0.1)", 1 )
-
-
-"""
-Test output:
->pythonw -u fourFn.py
-9 = 9.0 ['9'] => ['9']
-9 + 3 + 6 = 18.0 ['9', '+', '3', '+', '6'] => ['9', '3', '+', '6', '+']
-9 + 3 / 11 = 9.27272727273 ['9', '+', '3', '/', '11'] => ['9', '3', '11', '/', '+']
-(9 + 3) = 12.0 [] => ['9', '3', '+']
-(9+3) / 11 = 1.09090909091 ['/', '11'] => ['9', '3', '+', '11', '/']
-9 - 12 - 6 = -9.0 ['9', '-', '12', '-', '6'] => ['9', '12', '-', '6', '-']
-9 - (12 - 6) = 3.0 ['9', '-'] => ['9', '12', '6', '-', '-']
-2*3.14159 = 6.28318 ['2', '*', '3.14159'] => ['2', '3.14159', '*']
-3.1415926535*3.1415926535 / 10 = 0.986960440053 ['3.1415926535', '*', '3.1415926535', '/', '10'] => ['3.1415926535', '3.1415926535', '*', '10', '/']
-PI * PI / 10 = 0.986960440109 ['PI', '*', 'PI', '/', '10'] => ['PI', 'PI', '*', '10', '/']
-PI*PI/10 = 0.986960440109 ['PI', '*', 'PI', '/', '10'] => ['PI', 'PI', '*', '10', '/']
-PI^2 = 9.86960440109 ['PI', '^', '2'] => ['PI', '2', '^']
-6.02E23 * 8.048 = 4.844896e+024 ['6.02E23', '*', '8.048'] => ['6.02E23', '8.048', '*']
-e / 3 = 0.90609394282 ['E', '/', '3'] => ['E', '3', '/']
-sin(PI/2) = 1.0 ['sin', 'PI', '/', '2'] => ['PI', '2', '/', 'sin']
-trunc(E) = 2 ['trunc', 'E'] => ['E', 'trunc']
-E^PI = 23.1406926328 ['E', '^', 'PI'] => ['E', 'PI', '^']
-2^3^2 = 512.0 ['2', '^', '3', '^', '2'] => ['2', '3', '2', '^', '^']
-2^3+2 = 10.0 ['2', '^', '3', '+', '2'] => ['2', '3', '^', '2', '+']
-2^9 = 512.0 ['2', '^', '9'] => ['2', '9', '^']
-sgn(-2) = -1 ['sgn', '-2'] => ['-2', 'sgn']
-sgn(0) = 0 ['sgn', '0'] => ['0', 'sgn']
-sgn(0.1) = 1 ['sgn', '0.1'] => ['0.1', 'sgn']
->Exit code: 0
-"""
|