forked from GitHub/comp-syntax-gu-mlt
73 lines
1.7 KiB
Python
73 lines
1.7 KiB
Python
# a minimal query system for arithmetic, using Montague-style semantics
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# and an embedded GF grammar
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# examples: "is 131 prime", "2 + 2"
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# presupposes 'gf -make QueryEng (QuerySwe ...)'
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import pgf
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import sys
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# we assume this abstract syntax
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absmodule = "Query"
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# change this to change input language
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langname = absmodule + "Eng"
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# the meaning of "number" in unrestricted quantification
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allNumbers = range(1,10000)
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def answer(tree):
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"top level Query interpreter"
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fun,args = tree.unpack()
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if fun == "QWhether":
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ans = predicate(args[1])(value(args[0]))
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else: # QWhat
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ans = value(args[0])
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return str(ans)
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def predicate(property):
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"takes Property or Kind to int -> bool"
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prop,pargs = property.unpack()
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if prop == "PPrime":
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return prime
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else:
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print("property not available")
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def value(term):
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"takes Term to int, does not cover quantifiers"
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fun,args = term.unpack()
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if fun == "TElement":
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return value(args[0])
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elif fun == "EInteger":
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return int(args[0].unpack())
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elif fun == "ESum":
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return value(args[0]) + value(args[1])
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else:
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print("term not availeble")
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def prime(n):
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"simple way to decide if a positive number is prime"
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if n == 1:
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r = False
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else:
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r = True
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for k in range(2,n//2+1):
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if n % k == 0: return False
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return r
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def main():
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"main function to be called from stdio"
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# read in the grammar, set up the input language
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grammar = pgf.readPGF(absmodule + ".pgf")
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lang = grammar.languages[langname]
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# read a line of input, parse in lang, return answer
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line = input("")
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parseresult = lang.parse(line)
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prob,tree = parseresult.__next__()
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print(answer(tree))
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main()
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