70 lines
1.2 KiB
Python
70 lines
1.2 KiB
Python
"""
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Tests for developing a meta-circular interpreter, step-by-step.
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"""
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import operator as op
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from lis import run
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env_scm = """
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(define standard-env (list
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(list (quote +) +)
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(list (quote -) -)
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))
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standard-env
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"""
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def test_env_build():
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got = run(env_scm)
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assert got == [['+', op.add], ['-', op.sub]]
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scan_scm = """
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(define l (quote (a b c)))
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(define (scan what where)
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(if (null? where)
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()
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(if (eq? what (car where))
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what
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(scan what (cdr where))))
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)
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"""
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def test_scan():
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source = scan_scm + '(scan (quote a) l )'
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got = run(source)
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assert got == 'a'
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def test_scan_not_found():
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source = scan_scm + '(scan (quote z) l )'
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got = run(source)
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assert got == []
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lookup_scm = """
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(define env (list
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(list (quote +) +)
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(list (quote -) -)
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))
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(define (lookup what where)
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(if (null? where)
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()
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(if (eq? what (car (car where)))
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(car (cdr (car where)))
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(lookup what (cdr where))))
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)
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"""
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def test_lookup():
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source = lookup_scm + '(lookup (quote +) env)'
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got = run(source)
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assert got == op.add
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def test_lookup_not_found():
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source = lookup_scm + '(lookup (quote z) env )'
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got = run(source)
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assert got == []
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