/
lexical.cljc
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/
lexical.cljc
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; Copyright (c) Alan Thompson. All rights reserved.
; The use and distribution terms for this software are covered by the Eclipse Public
; License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can be found in the
; file epl-v10.html at the root of this distribution. By using this software in any
; fashion, you are agreeing to be bound by the terms of this license.
; You must not remove this notice, or any other, from this software.
(ns tupelo.lexical
"Utils for lexical sorting and searching"
(:require
[tupelo.core.impl :as impl]
[tupelo.schema :as tsk]
[schema.core :as s]
))
#?(:cljs (enable-console-print!))
;---------------------------------------------------------------------------------------------------
; comparison-class throws exceptions for some types that might be
; useful to include.
(s/defn comparison-class :- s/Str
"Returns a string specifying the comparison class to be used for sorting a piece of data."
[x :- s/Any]
(cond
(nil? x) "" ; empty string sorts first of all strings
; Lump all numbers together since Clojure's compare can compare them all to each other sensibly.
(number? x) "Type/Clojure-Number"
(keyword? x) "Type/Clojure-Keyword"
(char? x) "Type/Clojure-Character" ; #todo does this ever fire?
(string? x) "Type/Clojure-String"
(boolean? x) "Type/Clojure-Boolean"
(symbol? x) "Type/Clojure-Symbol"
; sequential? includes lists, conses, vectors, and seqs of just about any collection, although it is recommended not
; to use this to compare seqs of unordered collections like sets or maps (vectors should be OK). This should be
; everything we would want to compare using cmp-seq-lexi below. A clojure.lang.MapEntry also implements clojure.lang.Sequential,
; so we can sort {:a 1 :b 2} as if it were [[:a 1] [:b 2]].
; TBD: Does it leave anything out? Include anything it should not?
(sequential? x) "Type/Clojure-Sequential"
; NOTE: record case must preempt `(map? ...)` case below, since all records can be viewed as maps
(record? x) (let [type-str (tupelo.core.impl/type-name-str x)]
; (prn :comparison-class--record [type-str x])
type-str)
(set? x) "Type/Clojure-IPersistentSet"
(map? x) "Type/Clojure-IPersistentMap"
(impl/native-array? x) "Type/Platform-Native-Array"
; Comparable includes Boolean, Character, String, Clojure refs, and many others.
#?(:clj (instance? java.lang.Comparable x)
:cljs (satisfies? cljs.core/IComparable x))
(do
; (println :comparable-block x)
(tupelo.core.impl/type-name-str x))
:else (throw
(ex-info
(str "cc-cmp does not implement comparison of values with class name=" (tupelo.core.impl/type-name-str x))
{:value x}))))
(defn ^:no-doc compare-seq-lexi
[cmpr-fn x y]
(loop [x x
y y]
(if (seq x)
(if (seq y)
(let [c (cmpr-fn (first x) (first y))]
(if (zero? c)
(recur (rest x) (rest y))
c))
; else we reached end of y first, so x > y
1)
(if (seq y)
; we reached end of x first, so x < y
-1
; Sequences contain same elements. x = y
0))))
; The same result can be obtained by calling cmp-seq-lexi on two
; vectors, but cmp-vec-lexi should allocate less memory comparing
; vectors.
(defn ^:no-doc compare-vec-lexi
[cmpr-fn x y]
(let [x-len (count x)
y-len (count y)
len (min x-len y-len)]
(loop [i 0]
(if (== i len)
; If all elements 0..(len-1) are same, shorter vector comes
; first.
(clojure.core/compare x-len y-len)
(let [c (cmpr-fn (x i) (y i))]
(if (zero? c)
(recur (inc i))
c))))))
(defn ^:no-doc compare-array-lexi
[cmpr-fn x y]
(let [x-len (alength x)
y-len (alength y)
len (min x-len y-len)]
(loop [i 0]
(if (== i len)
; If all elements 0..(len-1) are same, shorter array comes
; first.
(clojure.core/compare x-len y-len)
(let [c (cmpr-fn (aget x i) (aget y i))]
(if (zero? c)
(recur (inc i))
c))))))
(defn compare-generic
[x y]
(let [x-class-str (comparison-class x)
y-class-str (comparison-class y)
;>> (println [x-class-str x])
;>> (println [y-class-str y])
compare-result (clojure.core/compare x-class-str y-class-str)]
(cond
(not= compare-result 0) compare-result ; different classes
; Compare sets to each other as sequences, with elements in
; sorted order.
(= x-class-str "Type/Clojure-IPersistentSet")
(compare-seq-lexi compare-generic (sort compare-generic x) (sort compare-generic y))
; Compare records to each other like maps below.
; NOTE: record case must preempt `(map? ...)` case below, since all records can be viewed as maps
(record? x) (compare-seq-lexi compare-generic
(sort-by key compare-generic (seq x))
(sort-by key compare-generic (seq y)))
; Compare maps to each other as sequences of [key val] pairs, with pairs in order sorted by key.
; Since keys are unique
(= x-class-str "Type/Clojure-IPersistentMap")
(compare-seq-lexi compare-generic
(sort-by key compare-generic (seq x)) ; sorted [[xk1 xv1] [xk2 xv2] ...]
(sort-by key compare-generic (seq y))) ; sorted [[yk1 yv1] [yk2 yv2] ...]
(= x-class-str "Type/Platform-Native-Array")
(compare-array-lexi compare-generic x y)
; Make a special check for two vectors, since cmp-vec-lexi
; should allocate less memory comparing them than
; cmp-seq-lexi. Both here and for comparing sequences, we
; must use cc-cmp recursively on the elements, because if
; we used compare we would lose the ability to compare
; elements with different types.
(and (vector? x) (vector? y)) (compare-vec-lexi compare-generic x y)
; This will compare any two sequences, if they are not both
; vectors, e.g. a vector and a list will be compared here.
(= x-class-str "Type/Clojure-Sequential")
(compare-seq-lexi compare-generic x y)
:else (clojure.core/compare x y))))
(s/defn compare-lex :- s/Int
[a :- tsk/Vec
b :- tsk/Vec]
(compare-generic a b))