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#!/usr/bin/env python
"""
This is an example of "prompt_toolkit.contrib.regular_languages" which
implements a little calculator.
Type for instance::
> add 4 4
> sub 4 4
> sin 3.14
This example shows how you can define the grammar of a regular language and how
to use variables in this grammar with completers and tokens attached.
"""
from __future__ import unicode_literals
from prompt_toolkit.completion import WordCompleter
from prompt_toolkit import prompt
from prompt_toolkit.contrib.regular_languages.compiler import compile
from prompt_toolkit.contrib.regular_languages.completion import GrammarCompleter
from prompt_toolkit.contrib.regular_languages.lexer import GrammarLexer
from prompt_toolkit.lexers import SimpleLexer
from prompt_toolkit.styles import Style
import math
operators1 = ['add', 'sub', 'div', 'mul']
operators2 = ['sqrt', 'log', 'sin', 'ln']
def create_grammar():
return compile("""
(\s* (?P<operator1>[a-z]+) \s+ (?P<var1>[0-9.]+) \s+ (?P<var2>[0-9.]+) \s*) |
(\s* (?P<operator2>[a-z]+) \s+ (?P<var1>[0-9.]+) \s*)
""")
example_style = Style.from_dict({
'operator': '#33aa33 bold',
'number': '#ff0000 bold',
'trailing-input': 'bg:#662222 #ffffff',
})
if __name__ == '__main__':
g = create_grammar()
lexer = GrammarLexer(g, lexers={
'operator1': SimpleLexer('class:operator'),
'operator2': SimpleLexer('class:operator'),
'var1': SimpleLexer('class:number'),
'var2': SimpleLexer('class:number'),
})
completer = GrammarCompleter(g, {
'operator1': WordCompleter(operators1),
'operator2': WordCompleter(operators2),
})
try:
# REPL loop.
while True:
# Read input and parse the result.
text = prompt('Calculate: ', lexer=lexer, completer=completer,
style=example_style)
m = g.match(text)
if m:
vars = m.variables()
else:
print('Invalid command\n')
continue
print(vars)
if vars.get('operator1') or vars.get('operator2'):
try:
var1 = float(vars.get('var1', 0))
var2 = float(vars.get('var2', 0))
except ValueError:
print('Invalid command (2)\n')
continue
# Turn the operator string into a function.
operator = {
'add': (lambda a, b: a + b),
'sub': (lambda a, b: a - b),
'mul': (lambda a, b: a * b),
'div': (lambda a, b: a / b),
'sin': (lambda a, b: math.sin(a)),
}[vars.get('operator1') or vars.get('operator2')]
# Execute and print the result.
print('Result: %s\n' % (operator(var1, var2)))
elif vars.get('operator2'):
print('Operator 2')
except EOFError:
pass
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