Rewrites the lookup to another expression. @param cc compilation context @return optimized or original expression @throws QueryException query exception
(final CompileContext cc)
| 74 | * @throws QueryException query exception |
| 75 | */ |
| 76 | private Expr opt(final CompileContext cc) throws QueryException { |
| 77 | final Expr input = exprs[0], keys = exprs[1]; |
| 78 | final long is = input.size(); |
| 79 | final long ks = keys.seqType().mayBeWrapped() || keys.has(Flag.NDT) ? -1 : keys.size(); |
| 80 | if(ks == 0) return keys; |
| 81 | |
| 82 | final Type it = input.seqType().type; |
| 83 | final boolean map = it instanceof MapType, array = it instanceof ArrayType; |
| 84 | if(map || array) { |
| 85 | /* REWRITE LOOKUP: |
| 86 | * MAP?* → map:items(MAP) |
| 87 | * ARRAY?* → array:items(MAP) |
| 88 | * MAP?KEY → map:get(INPUT, KEY) |
| 89 | * ARRAY?KEY → array:get(INPUT, KEY) */ |
| 90 | final QueryBiFunction<Expr, Expr, Expr> rewrite = (in, arg) -> keys == WILDCARD ? |
| 91 | cc.function(map ? Function._MAP_ITEMS : Function._ARRAY_ITEMS, info, in) : |
| 92 | cc.function(map ? Function._MAP_GET : Function._ARRAY_GET, info, in, arg); |
| 93 | |
| 94 | // single key |
| 95 | if(ks == 1) { |
| 96 | // single input: INPUT?KEY → REWRITE(INPUT, KEY) |
| 97 | if(is == 1) return rewrite.apply(input, keys); |
| 98 | // multiple inputs: INPUTS?KEY → INPUTS ! REWRITE(., KEY) |
| 99 | return SimpleMap.get(cc, info, input, |
| 100 | cc.get(input, true, () -> rewrite.apply(ContextValue.get(cc, info), keys))); |
| 101 | } |
| 102 | |
| 103 | // multiple deterministic keys, inputs are values or variable references |
| 104 | if(ks != -1 && (input instanceof Value || input instanceof VarRef)) { |
| 105 | // single input: INPUT?KEYS → KEYS ! REWRITE(INPUT, .) |
| 106 | if(is == 1) return SimpleMap.get(cc, info, keys, |
| 107 | cc.get(keys, true, () -> rewrite.apply(input, ContextValue.get(cc, info)))); |
| 108 | // multiple inputs: INPUT?KEYS → for $item in INPUT return KEYS ! REWRITE($item, .) |
| 109 | final FLWORBuilder flwor = new FLWORBuilder(1, cc, info); |
| 110 | final Expr next = cc.get(keys, true, () -> |
| 111 | rewrite.apply(flwor.ref(flwor.item), ContextValue.get(cc, info))); |
| 112 | final Expr rtrn = SimpleMap.get(cc, info, keys, next); |
| 113 | return flwor.finish(input, null, rtrn); |
| 114 | } |
| 115 | } |
| 116 | return this; |
| 117 | } |
| 118 | |
| 119 | @Override |
| 120 | public Iter iter(final QueryContext qc) throws QueryException { |