a S/b1@sddlmZddlmZmZddZddZGdddZGd d d Zed Z ed Z Gd dde Z GdddZ GdddZddZddZeedZddZddZdS))deque)istasksubscCs&t|r|dSt|trtS|SdS)z#Return the top level node of a taskrNr isinstancelisttaskr +lib/python3.9/site-packages/dask/rewrite.pyheads  r cCs*t|r|ddSt|tr"|SdSdS)z&Get the arguments for the current taskNr rrr r r argss   rc@sFeZdZdZdddZddZddZd d Zed d Z d dZ dS) TraverseraTraverser interface for tasks. Class for storing the state while performing a preorder-traversal of a task. Parameters ---------- term : task The task to be traversed Attributes ---------- term The current element in the traversal current The head of the current element in the traversal. This is simply `head` applied to the attribute `term`. NcCs"||_|sttg|_n||_dSN)termrEND_stack)selfrstackr r r __init__0szTraverser.__init__ccs |jtur|jV|qdSr)currentrnextrr r r __iter__7s zTraverser.__iter__cCst|jt|jS)zCopy the traverser in its current state. This allows the traversal to be pushed onto a stack, for easy backtracking.)rrrrrr r r copy<szTraverser.copycCsBt|j}|s|j|_n"|d|_|jt|dddS)z3Proceed to the next term in the preorder traversal.rr N)rrrpopextendreversed)rZsubtermsr r r rDs   zTraverser.nextcCs t|jSr)r rrr r r rOszTraverser.currentcCs|j|_dS)z `rhs`, for variables `vars`. Parameters ---------- lhs : task The left-hand-side of the rewrite rule. rhs : task or function The right-hand-side of the rewrite rule. If it's a task, variables in `rhs` will be replaced by terms in the subject that match the variables in `lhs`. If it's a function, the function will be called with a dict of such matches. vars: tuple, optional Tuple of variables found in the lhs. Variables can be represented as any hashable object; a good convention is to use strings. If there are no variables, this can be omitted. Examples -------- Here's a `RewriteRule` to replace all nested calls to `list`, so that `(list, (list, 'x'))` is replaced with `(list, 'x')`, where `'x'` is a variable. >>> import dask.rewrite as dr >>> lhs = (list, (list, 'x')) >>> rhs = (list, 'x') >>> variables = ('x',) >>> rule = dr.RewriteRule(lhs, rhs, variables) Here's a more complicated rule that uses a callable right-hand-side. A callable `rhs` takes in a dictionary mapping variables to their matching values. This rule replaces all occurrences of `(list, 'x')` with `'x'` if `'x'` is a list itself. >>> lhs = (list, 'x') >>> def repl_list(sd): ... x = sd['x'] ... if isinstance(x, list): ... return x ... else: ... return (list, x) >>> rule = dr.RewriteRule(lhs, repl_list, variables) r csfttstd||_t|r(||_n|j|_||_fddt|D|_ tt t |j |_ dS)Nz!vars must be a tuple of variablescsg|]}|vr|qSr r .0tvarsr r z(RewriteRule.__init__..) rr, TypeErrorlhscallabler_applyrhsr_varlistsortedsetr7)rr;r>r7r r6r rs zRewriteRule.__init__cCs(|j}|D]\}}t|||}q|Sr)r>itemsr)rZsub_dictrkeyvalr r r r=szRewriteRule._applycCsd|jd|jd|jdS)Nz RewriteRule(z, ))r;r>r7rr r r __str__szRewriteRule.__str__cCst|Sr)strrr r r r(szRewriteRule.__repr__N)r )r r!r"r#rr=rFr(r r r r r2s - r2c@s:eZdZdZddZddZddZdd Zdd d Zd S)RuleSeta%A set of rewrite rules. Forms a structure for fast rewriting over a set of rewrite rules. This allows for syntactic matching of terms to patterns for many patterns at the same time. Examples -------- >>> import dask.rewrite as dr >>> def f(*args): pass >>> def g(*args): pass >>> def h(*args): pass >>> from operator import add >>> rs = dr.RuleSet( ... dr.RewriteRule((add, 'x', 0), 'x', ('x',)), ... dr.RewriteRule((f, (g, 'x'), 'y'), ... (h, 'x', 'y'), ... ('x', 'y'))) >>> rs.rewrite((add, 2, 0)) 2 >>> rs.rewrite((f, (g, 'a', 3))) # doctest: +ELLIPSIS (, 'a', 3) >>> dsk = {'a': (add, 2, 0), ... 'b': (f, (g, 'a', 3))} >>> from toolz import valmap >>> valmap(rs.rewrite, dsk) # doctest: +ELLIPSIS {'a': 2, 'b': (, 'a', 3)} Attributes ---------- rules : list A list of `RewriteRule`s included in the `RuleSet`. cGs&t|_g|_|D]}||qdS)zCreate a `RuleSet` for a number of rules Parameters ---------- rules One or more instances of RewriteRule N)r+_netrulesadd)rrJpr r r rszRuleSet.__init__cCst|tstd|j}|j}t|j}t|jD]@}|}||vrFt }||j vr\|j |}q2t |j |<|j |}q2|j |j ||j |dS)zeAdd a rule to the RuleSet. Parameters ---------- rule : RewriteRule z$rule must be instance of RewriteRuleN)rr2r:r7rIlenrJrr;VARr/r+r0append)rruler7Z curr_nodeZindr5Z prev_noder r r rKs      z RuleSet.addccsRt|}t||jD]8\}}|D]*}|j|}t||}|dur ||fVq qdS)alA generator that lazily finds matchings for term from the RuleSet. Parameters ---------- term : task Yields ------ Tuples of `(rule, subs)`, where `rule` is the rewrite rule being matched, and `subs` is a dictionary mapping the variables in the lhs of the rule to their matching values in the term.N)r_matchrIrJ_process_match)rrSmsymsirPrr r r iter_matchess   zRuleSet.iter_matchescCs&||D]\}}||}q"q |S)z7Apply the rewrite rules in RuleSet to top level of term)rWr)rrrPsdr r r _rewrite.s zRuleSet._rewrite bottom_upcCst|||S)aeApply the `RuleSet` to `task`. This applies the most specific matching rule in the RuleSet to the task, using the provided strategy. Parameters ---------- term: a task The task to be rewritten strategy: str, optional The rewriting strategy to use. Options are "bottom_up" (default), or "top_level". Examples -------- Suppose there was a function `add` that returned the sum of 2 numbers, and another function `double` that returned twice its input: >>> add = lambda x, y: x + y >>> double = lambda x: 2*x Now suppose `double` was *significantly* faster than `add`, so you'd like to replace all expressions `(add, x, x)` with `(double, x)`, where `x` is a variable. This can be expressed as a rewrite rule: >>> rule = RewriteRule((add, 'x', 'x'), (double, 'x'), ('x',)) >>> rs = RuleSet(rule) This can then be applied to terms to perform the rewriting: >>> term = (add, (add, 2, 2), (add, 2, 2)) >>> rs.rewrite(term) # doctest: +SKIP (double, (double, 2)) If we only wanted to apply this to the top level of the term, the `strategy` kwarg can be set to "top_level". >>> rs.rewrite(term) # doctest: +SKIP (double, (add, 2, 2)) ) strategies)rr Zstrategyr r r rewrite9s)zRuleSet.rewriteN)rZ) r r!r"r#rrKrWrYr\r r r r rHs (  rHcCs ||Sr)rYnetrr r r _top_levelesr_csXt|r.t|ftfddt|D}n t|trNfddt|D}|S)Nc3s|]}t|VqdSr _bottom_upr3r^r r kr9z_bottom_up..csg|]}t|qSr r`r3rbr r r8mr9z_bottom_up..)rr r,rrrrYr]r rbr rais & ra)Z top_levelrZccst}d}d}|jtur$|j|fVz@|j|jd}|rb|sb||||f|}|WqWnt yvYn0|jt d}|rd}||j f}| |}qz| \}}}d}WqtyYdS0qdS)z;Structural matching of term S to discrimination net node N.Fr NT)rrrr0r/getrOrrr:rNrrr Exception)rSNrZrestore_state_flagmatchesnr r r rQts4     rQcCs\i}|j}t|t|ks"tdt||D]*\}}||vrN|||krNdS|||<q,|S)aProcess a match to determine if it is correct, and to find the correct substitution that will convert the term into the pattern. Parameters ---------- rule : RewriteRule syms : iterable Iterable of subterms that match a corresponding variable. Returns ------- A dictionary of {vars : subterms} describing the substitution to make the pattern equivalent with the term. Returns `None` if the match is invalid.z/length of varlist doesn't match length of syms.N)r?rM RuntimeErrorzip)rPrUrZvarlistvsr r r rRs rRN) collectionsrZ dask.corerrr rrr%rNrr,r+r2rHr_rar[rQrRr r r r s   < H &