Java example source code file (pretty_writer.clj)
The pretty_writer.clj Java example source code;;; pretty_writer.clj -- part of the pretty printer for Clojure
; Copyright (c) Rich Hickey. 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.
;; Author: Tom Faulhaber
;; April 3, 2009
;; Revised to use proxy instead of gen-class April 2010
;; This module implements a wrapper around a java.io.Writer which implements the
;; core of the XP algorithm.
(in-ns 'clojure.pprint)
(import [clojure.lang IDeref]
[java.io Writer])
;; TODO: Support for tab directives
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Forward declarations
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(declare get-miser-width)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Macros to simplify dealing with types and classes. These are
;;; really utilities, but I'm experimenting with them here.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defmacro ^{:private true}
getf
"Get the value of the field named by the argument (which should be a keyword)."
[sym]
`(~sym @@~'this))
(defmacro ^{:private true}
setf [sym new-val]
"Set the value of the field SYM to NEW-VAL"
`(alter @~'this assoc ~sym ~new-val))
(defmacro ^{:private true}
deftype [type-name & fields]
(let [name-str (name type-name)]
`(do
(defstruct ~type-name :type-tag ~@fields)
(alter-meta! #'~type-name assoc :private true)
(defn- ~(symbol (str "make-" name-str))
[& vals#] (apply struct ~type-name ~(keyword name-str) vals#))
(defn- ~(symbol (str name-str "?")) [x#] (= (:type-tag x#) ~(keyword name-str))))))
(defmacro ^{:private true}
write-to-base
"Call .write on Writer (getf :base) with proper type-hinting to
avoid reflection."
[& args]
`(let [^Writer w# (getf :base)]
(.write w# ~@args)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; The data structures used by pretty-writer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defstruct ^{:private true} logical-block
:parent :section :start-col :indent
:done-nl :intra-block-nl
:prefix :per-line-prefix :suffix
:logical-block-callback)
(defn- ancestor? [parent child]
(loop [child (:parent child)]
(cond
(nil? child) false
(identical? parent child) true
:else (recur (:parent child)))))
(defstruct ^{:private true} section :parent)
(defn- buffer-length [l]
(let [l (seq l)]
(if l
(- (:end-pos (last l)) (:start-pos (first l)))
0)))
; A blob of characters (aka a string)
(deftype buffer-blob :data :trailing-white-space :start-pos :end-pos)
; A newline
(deftype nl-t :type :logical-block :start-pos :end-pos)
(deftype start-block-t :logical-block :start-pos :end-pos)
(deftype end-block-t :logical-block :start-pos :end-pos)
(deftype indent-t :logical-block :relative-to :offset :start-pos :end-pos)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Functions to write tokens in the output buffer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(def ^:private pp-newline (memoize #(System/getProperty "line.separator")))
(declare emit-nl)
(defmulti ^{:private true} write-token #(:type-tag %2))
(defmethod write-token :start-block-t [^Writer this token]
(when-let [cb (getf :logical-block-callback)] (cb :start))
(let [lb (:logical-block token)]
(dosync
(when-let [^String prefix (:prefix lb)]
(write-to-base prefix))
(let [col (get-column (getf :base))]
(ref-set (:start-col lb) col)
(ref-set (:indent lb) col)))))
(defmethod write-token :end-block-t [^Writer this token]
(when-let [cb (getf :logical-block-callback)] (cb :end))
(when-let [^String suffix (:suffix (:logical-block token))]
(write-to-base suffix)))
(defmethod write-token :indent-t [^Writer this token]
(let [lb (:logical-block token)]
(ref-set (:indent lb)
(+ (:offset token)
(condp = (:relative-to token)
:block @(:start-col lb)
:current (get-column (getf :base)))))))
(defmethod write-token :buffer-blob [^Writer this token]
(write-to-base ^String (:data token)))
(defmethod write-token :nl-t [^Writer this token]
; (prlabel wt @(:done-nl (:logical-block token)))
; (prlabel wt (:type token) (= (:type token) :mandatory))
(if (or (= (:type token) :mandatory)
(and (not (= (:type token) :fill))
@(:done-nl (:logical-block token))))
(emit-nl this token)
(if-let [^String tws (getf :trailing-white-space)]
(write-to-base tws)))
(dosync (setf :trailing-white-space nil)))
(defn- write-tokens [^Writer this tokens force-trailing-whitespace]
(doseq [token tokens]
(if-not (= (:type-tag token) :nl-t)
(if-let [^String tws (getf :trailing-white-space)]
(write-to-base tws)))
(write-token this token)
(setf :trailing-white-space (:trailing-white-space token)))
(let [^String tws (getf :trailing-white-space)]
(when (and force-trailing-whitespace tws)
(write-to-base tws)
(setf :trailing-white-space nil))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; emit-nl? method defs for each type of new line. This makes
;;; the decision about whether to print this type of new line.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defn- tokens-fit? [^Writer this tokens]
;;; (prlabel tf? (get-column (getf :base) (buffer-length tokens))
(let [maxcol (get-max-column (getf :base))]
(or
(nil? maxcol)
(< (+ (get-column (getf :base)) (buffer-length tokens)) maxcol))))
(defn- linear-nl? [this lb section]
; (prlabel lnl? @(:done-nl lb) (tokens-fit? this section))
(or @(:done-nl lb)
(not (tokens-fit? this section))))
(defn- miser-nl? [^Writer this lb section]
(let [miser-width (get-miser-width this)
maxcol (get-max-column (getf :base))]
(and miser-width maxcol
(>= @(:start-col lb) (- maxcol miser-width))
(linear-nl? this lb section))))
(defmulti ^{:private true} emit-nl? (fn [t _ _ _] (:type t)))
(defmethod emit-nl? :linear [newl this section _]
(let [lb (:logical-block newl)]
(linear-nl? this lb section)))
(defmethod emit-nl? :miser [newl this section _]
(let [lb (:logical-block newl)]
(miser-nl? this lb section)))
(defmethod emit-nl? :fill [newl this section subsection]
(let [lb (:logical-block newl)]
(or @(:intra-block-nl lb)
(not (tokens-fit? this subsection))
(miser-nl? this lb section))))
(defmethod emit-nl? :mandatory [_ _ _ _]
true)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Various support functions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defn- get-section [buffer]
(let [nl (first buffer)
lb (:logical-block nl)
section (seq (take-while #(not (and (nl-t? %) (ancestor? (:logical-block %) lb)))
(next buffer)))]
[section (seq (drop (inc (count section)) buffer))]))
(defn- get-sub-section [buffer]
(let [nl (first buffer)
lb (:logical-block nl)
section (seq (take-while #(let [nl-lb (:logical-block %)]
(not (and (nl-t? %) (or (= nl-lb lb) (ancestor? nl-lb lb)))))
(next buffer)))]
section))
(defn- update-nl-state [lb]
(dosync
(ref-set (:intra-block-nl lb) false)
(ref-set (:done-nl lb) true)
(loop [lb (:parent lb)]
(if lb
(do (ref-set (:done-nl lb) true)
(ref-set (:intra-block-nl lb) true)
(recur (:parent lb)))))))
(defn- emit-nl [^Writer this nl]
(write-to-base ^String (pp-newline))
(dosync (setf :trailing-white-space nil))
(let [lb (:logical-block nl)
^String prefix (:per-line-prefix lb)]
(if prefix
(write-to-base prefix))
(let [^String istr (apply str (repeat (- @(:indent lb) (count prefix))
\space))]
(write-to-base istr))
(update-nl-state lb)))
(defn- split-at-newline [tokens]
(let [pre (seq (take-while #(not (nl-t? %)) tokens))]
[pre (seq (drop (count pre) tokens))]))
;;; Methods for showing token strings for debugging
(defmulti ^{:private true} tok :type-tag)
(defmethod tok :nl-t [token]
(:type token))
(defmethod tok :buffer-blob [token]
(str \" (:data token) (:trailing-white-space token) \"))
(defmethod tok :default [token]
(:type-tag token))
(defn- toks [toks] (map tok toks))
;;; write-token-string is called when the set of tokens in the buffer
;;; is longer than the available space on the line
(defn- write-token-string [this tokens]
(let [[a b] (split-at-newline tokens)]
;; (prlabel wts (toks a) (toks b))
(if a (write-tokens this a false))
(if b
(let [[section remainder] (get-section b)
newl (first b)]
;; (prlabel wts (toks section)) (prlabel wts (:type newl)) (prlabel wts (toks remainder))
(let [do-nl (emit-nl? newl this section (get-sub-section b))
result (if do-nl
(do
;; (prlabel emit-nl (:type newl))
(emit-nl this newl)
(next b))
b)
long-section (not (tokens-fit? this result))
result (if long-section
(let [rem2 (write-token-string this section)]
;;; (prlabel recurse (toks rem2))
(if (= rem2 section)
(do ; If that didn't produce any output, it has no nls
; so we'll force it
(write-tokens this section false)
remainder)
(into [] (concat rem2 remainder))))
result)
;; ff (prlabel wts (toks result))
]
result)))))
(defn- write-line [^Writer this]
(dosync
(loop [buffer (getf :buffer)]
;; (prlabel wl1 (toks buffer))
(setf :buffer (into [] buffer))
(if (not (tokens-fit? this buffer))
(let [new-buffer (write-token-string this buffer)]
;; (prlabel wl new-buffer)
(if-not (identical? buffer new-buffer)
(recur new-buffer)))))))
;;; Add a buffer token to the buffer and see if it's time to start
;;; writing
(defn- add-to-buffer [^Writer this token]
; (prlabel a2b token)
(dosync
(setf :buffer (conj (getf :buffer) token))
(if (not (tokens-fit? this (getf :buffer)))
(write-line this))))
;;; Write all the tokens that have been buffered
(defn- write-buffered-output [^Writer this]
(write-line this)
(if-let [buf (getf :buffer)]
(do
(write-tokens this buf true)
(setf :buffer []))))
(defn- write-white-space [^Writer this]
(when-let [^String tws (getf :trailing-white-space)]
; (prlabel wws (str "*" tws "*"))
(write-to-base tws)
(dosync
(setf :trailing-white-space nil))))
;;; If there are newlines in the string, print the lines up until the last newline,
;;; making the appropriate adjustments. Return the remainder of the string
(defn- write-initial-lines
[^Writer this ^String s]
(let [lines (.split s "\n" -1)]
(if (= (count lines) 1)
s
(dosync
(let [^String prefix (:per-line-prefix (first (getf :logical-blocks)))
^String l (first lines)]
(if (= :buffering (getf :mode))
(let [oldpos (getf :pos)
newpos (+ oldpos (count l))]
(setf :pos newpos)
(add-to-buffer this (make-buffer-blob l nil oldpos newpos))
(write-buffered-output this))
(do
(write-white-space this)
(write-to-base l)))
(write-to-base (int \newline))
(doseq [^String l (next (butlast lines))]
(write-to-base l)
(write-to-base ^String (pp-newline))
(if prefix
(write-to-base prefix)))
(setf :buffering :writing)
(last lines))))))
(defn- p-write-char [^Writer this ^Integer c]
(if (= (getf :mode) :writing)
(do
(write-white-space this)
(write-to-base c))
(if (= c \newline)
(write-initial-lines this "\n")
(let [oldpos (getf :pos)
newpos (inc oldpos)]
(dosync
(setf :pos newpos)
(add-to-buffer this (make-buffer-blob (str (char c)) nil oldpos newpos)))))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Initialize the pretty-writer instance
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defn- pretty-writer [writer max-columns miser-width]
(let [lb (struct logical-block nil nil (ref 0) (ref 0) (ref false) (ref false))
fields (ref {:pretty-writer true
:base (column-writer writer max-columns)
:logical-blocks lb
:sections nil
:mode :writing
:buffer []
:buffer-block lb
:buffer-level 1
:miser-width miser-width
:trailing-white-space nil
:pos 0})]
(proxy [Writer IDeref PrettyFlush] []
(deref [] fields)
(write
([x]
;; (prlabel write x (getf :mode))
(condp = (class x)
String
(let [^String s0 (write-initial-lines this x)
^String s (.replaceFirst s0 "\\s+$" "")
white-space (.substring s0 (count s))
mode (getf :mode)]
(dosync
(if (= mode :writing)
(do
(write-white-space this)
(write-to-base s)
(setf :trailing-white-space white-space))
(let [oldpos (getf :pos)
newpos (+ oldpos (count s0))]
(setf :pos newpos)
(add-to-buffer this (make-buffer-blob s white-space oldpos newpos))))))
Integer
(p-write-char this x)
Long
(p-write-char this x)))
([x off len]
(.write ^Writer this (subs (str x) off (+ off len)))))
(ppflush []
(if (= (getf :mode) :buffering)
(dosync
(write-tokens this (getf :buffer) true)
(setf :buffer []))
(write-white-space this)))
(flush []
(.ppflush ^PrettyFlush this)
(let [^Writer w (getf :base)]
(.flush w)))
(close []
(.flush ^Writer this)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Methods for pretty-writer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defn- start-block
[^Writer this
^String prefix ^String per-line-prefix ^String suffix]
(dosync
(let [lb (struct logical-block (getf :logical-blocks) nil (ref 0) (ref 0)
(ref false) (ref false)
prefix per-line-prefix suffix)]
(setf :logical-blocks lb)
(if (= (getf :mode) :writing)
(do
(write-white-space this)
(when-let [cb (getf :logical-block-callback)] (cb :start))
(if prefix
(write-to-base prefix))
(let [col (get-column (getf :base))]
(ref-set (:start-col lb) col)
(ref-set (:indent lb) col)))
(let [oldpos (getf :pos)
newpos (+ oldpos (if prefix (count prefix) 0))]
(setf :pos newpos)
(add-to-buffer this (make-start-block-t lb oldpos newpos)))))))
(defn- end-block [^Writer this]
(dosync
(let [lb (getf :logical-blocks)
^String suffix (:suffix lb)]
(if (= (getf :mode) :writing)
(do
(write-white-space this)
(if suffix
(write-to-base suffix))
(when-let [cb (getf :logical-block-callback)] (cb :end)))
(let [oldpos (getf :pos)
newpos (+ oldpos (if suffix (count suffix) 0))]
(setf :pos newpos)
(add-to-buffer this (make-end-block-t lb oldpos newpos))))
(setf :logical-blocks (:parent lb)))))
(defn- nl [^Writer this type]
(dosync
(setf :mode :buffering)
(let [pos (getf :pos)]
(add-to-buffer this (make-nl-t type (getf :logical-blocks) pos pos)))))
(defn- indent [^Writer this relative-to offset]
(dosync
(let [lb (getf :logical-blocks)]
(if (= (getf :mode) :writing)
(do
(write-white-space this)
(ref-set (:indent lb)
(+ offset (condp = relative-to
:block @(:start-col lb)
:current (get-column (getf :base))))))
(let [pos (getf :pos)]
(add-to-buffer this (make-indent-t lb relative-to offset pos pos)))))))
(defn- get-miser-width [^Writer this]
(getf :miser-width))
(defn- set-miser-width [^Writer this new-miser-width]
(dosync (setf :miser-width new-miser-width)))
(defn- set-logical-block-callback [^Writer this f]
(dosync (setf :logical-block-callback f)))
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