Merge pull request #1792 from refi64/while-cond
Rework statements in while condition
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commit
cf91e16235
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NEWS.rst
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NEWS.rst
@ -12,6 +12,7 @@ Removals
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Bug Fixes
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------------------------------
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* Statements in the second argument of `assert` are now executed.
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* Fixed the expression of a while loop that contains statements being compiled twice.
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0.17.0
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==============================
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@ -1373,33 +1373,46 @@ class HyASTCompiler(object):
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def compile_while_expression(self, expr, root, cond, body, else_expr):
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cond_compiled = self.compile(cond)
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body = self._compile_branch(body)
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body += body.expr_as_stmt()
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body_stmts = body.stmts or [asty.Pass(expr)]
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if cond_compiled.stmts:
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# We need to ensure the statements for the condition are
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# executed on every iteration. Rewrite the loop to use a
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# single anonymous variable as the condition.
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cond_var = self.get_anon_var()
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return self.compile(mkexpr(
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'do',
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mkexpr('setv', cond_var, 'True'),
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mkexpr('while', cond_var,
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# Cast the condition to a bool in case it's mutable and
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# changes its truth value, but use (not (not ...)) instead of
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# `bool` in case `bool` has been redefined.
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mkexpr('setv', cond_var, mkexpr('not', mkexpr('not', [cond]))),
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mkexpr('if*', cond_var, mkexpr('do', rest=body)),
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*([mkexpr('else', rest=else_expr)] if else_expr is not None else []))).replace(expr)) # noqa
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# single anonymous variable as the condition, i.e.:
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# anon_var = True
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# while anon_var:
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# condition stmts...
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# anon_var = condition expr
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# if anon_var:
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# while loop body
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cond_var = asty.Name(cond, id=self.get_anon_var(), ctx=ast.Load())
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def make_not(operand):
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return asty.UnaryOp(cond, op=ast.Not(), operand=operand)
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body_stmts = cond_compiled.stmts + [
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asty.Assign(cond, targets=[self._storeize(cond, cond_var)],
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# Cast the condition to a bool in case it's mutable and
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# changes its truth value, but use (not (not ...)) instead of
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# `bool` in case `bool` has been redefined.
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value=make_not(make_not(cond_compiled.force_expr))),
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asty.If(cond, test=cond_var, body=body_stmts, orelse=[]),
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]
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cond_compiled = (Result()
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+ asty.Assign(cond, targets=[self._storeize(cond, cond_var)],
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value=asty.Name(cond, id="True", ctx=ast.Load()))
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+ cond_var)
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orel = Result()
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if else_expr is not None:
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orel = self._compile_branch(else_expr)
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orel += orel.expr_as_stmt()
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body = self._compile_branch(body)
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body += body.expr_as_stmt()
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ret = cond_compiled + asty.While(
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expr, test=cond_compiled.force_expr,
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body=body.stmts or [asty.Pass(expr)],
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body=body_stmts,
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orelse=orel.stmts)
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return ret
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@ -197,7 +197,23 @@
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(.append l 1)
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(len l))
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(while (!= (f) 4) (do))
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(assert (= l [1 1 1 1])))
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(assert (= l [1 1 1 1]))
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; only compile the condition once
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; https://github.com/hylang/hy/issues/1790
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(global while-cond-var)
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(setv while-cond-var 10)
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(eval
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'(do
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(defmacro while-cond []
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(global while-cond-var)
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(assert (= while-cond-var 10))
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(+= while-cond-var 1)
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`(do
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(setv x 3)
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False))
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(while (while-cond))
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(assert (= x 3)))))
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(defn test-while-loop-else []
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(setv count 5)
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