instructions.lisp

   1 ;;; -*- show-trailing-whitespace: t; indent-tabs: nil -*-
   2
   3 ;;; Copyright (c) 2007,2008 David Lichteblau, Ivan Shvedunov.
   4 ;;; All rights reserved.
   5
   6 ;;; Redistribution and use in source and binary forms, with or without
   7 ;;; modification, are permitted provided that the following conditions
   8 ;;; are met:
   9 ;;;
  10 ;;;   * Redistributions of source code must retain the above copyright
  11 ;;;     notice, this list of conditions and the following disclaimer.
  12 ;;;
  13 ;;;   * Redistributions in binary form must reproduce the above
  14 ;;;     copyright notice, this list of conditions and the following
  15 ;;;     disclaimer in the documentation and/or other materials
  16 ;;;     provided with the distribution.
  17 ;;;
  18 ;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
  19 ;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  20 ;;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21 ;;; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  22 ;;; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23 ;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  24 ;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  25 ;;; INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  26 ;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  27 ;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  28 ;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 (in-package :xuriella)
  31
  32 #+sbcl
  33 (declaim (optimize (debug 2)))
  34
  35
  36 ;;;; Instructions
  37
  38 (defmacro define-instruction (name (args-var env-var) &body body)
  39   `(setf (get ',name 'xslt-instruction)
  40          (lambda (,args-var ,env-var)
  41            (declare (ignorable ,env-var))
  42            ,@body)))
  43
  44 (define-instruction if (args env)
  45   (destructuring-bind (test then &optional else) args
  46     (let ((test-thunk (compile-xpath test env))
  47           (then-thunk (compile-instruction then env))
  48           (else-thunk (when else (compile-instruction else env))))
  49       (lambda (ctx)
  50         (cond
  51           ((xpath:boolean-value (funcall test-thunk ctx))
  52            (funcall then-thunk ctx))
  53           (else-thunk
  54            (funcall else-thunk ctx)))))))
  55
  56 (define-instruction when (args env)
  57   (destructuring-bind (test &rest body) args
  58     (compile-instruction `(if ,test (progn ,@body)) env)))
  59
  60 (define-instruction unless (args env)
  61   (destructuring-bind (test &rest body) args
  62     (compile-instruction `(if (:not ,test) (progn ,@body)) env)))
  63
  64 (define-instruction cond (args env)
  65   (if args
  66       (destructuring-bind ((test &body body) &rest clauses) args
  67         (compile-instruction (if (eq test t)
  68                                  `(progn ,@body)
  69                                  `(if ,test
  70                                       (progn ,@body)
  71                                       (cond ,@clauses)))
  72                              env))
  73       (constantly nil)))
  74
  75 (define-instruction progn (args env)
  76   (if args
  77       (let ((first-thunk (compile-instruction (first args) env))
  78             (rest-thunk (compile-instruction `(progn ,@(rest args)) env)))
  79         (lambda (ctx)
  80           (funcall first-thunk ctx)
  81           (funcall rest-thunk ctx)))
  82       (constantly nil)))
  83
  84 (defun decode-qname/runtime (qname namespaces attributep)
  85   (handler-case
  86       (multiple-value-bind (prefix local-name)
  87           (split-qname qname)
  88         (values local-name
  89                 (if (or prefix (not attributep))
  90                     (cdr (assoc prefix namespaces :test 'equal))
  91                     "")
  92                 prefix))
  93     (cxml:well-formedness-violation ()
  94       (xslt-error "not a qname: ~A" qname))))
  95
  96 (define-instruction xsl:element (args env)
  97   (destructuring-bind ((name &key namespace use-attribute-sets)
  98                        &body body)
  99       args
 100     (declare (ignore use-attribute-sets)) ;fixme
 101     (multiple-value-bind (name-thunk constant-name-p)
 102         (compile-avt name env)
 103       (multiple-value-bind (ns-thunk constant-ns-p)
 104           (if namespace
 105               (compile-avt namespace env)
 106               (values nil t))
 107         (let ((body-thunk (compile-instruction `(progn ,@body) env)))
 108           (if (and constant-name-p constant-ns-p)
 109               (compile-element/constant-name name namespace env body-thunk)
 110               (compile-element/runtime name-thunk ns-thunk body-thunk)))))))
 111
 112 (defun compile-element/constant-name (qname namespace env body-thunk)
 113   ;; the simple case: compile-time decoding of the QName
 114   (multiple-value-bind (local-name uri prefix)
 115       (decode-qname qname env nil)
 116     (when namespace
 117       (setf uri namespace))
 118     (lambda (ctx)
 119       (with-element (local-name uri :suggested-prefix prefix)
 120         (funcall body-thunk ctx)))))
 121
 122 (defun compile-element/runtime (name-thunk ns-thunk body-thunk)
 123   ;; run-time decoding of the QName, but using the same namespaces
 124   ;; that would have been known at compilation time.
 125   (let ((namespaces *namespaces*))
 126     (lambda (ctx)
 127       (let ((qname (funcall name-thunk ctx)))
 128         (multiple-value-bind (local-name uri prefix)
 129             (decode-qname/runtime qname namespaces nil)
 130           (when ns-thunk
 131             (setf uri (funcall ns-thunk ctx)))
 132           (unless uri
 133             (setf uri ""))
 134           (with-element (local-name uri :suggested-prefix prefix)
 135             (funcall body-thunk ctx)))))))
 136
 137 (define-instruction xsl:use-attribute-sets (args env)
 138   (destructuring-bind (str) args
 139     (let ((sets (mapcar (lambda (qname)
 140                           (multiple-value-list (decode-qname qname env nil)))
 141                         (words str))))
 142       (lambda (ctx)
 143         (loop for (local-name uri nil) in sets do
 144              (dolist (thunk (find-attribute-set local-name uri))
 145                (funcall thunk ctx)))))))
 146
 147 (define-instruction xsl:attribute (args env)
 148   (destructuring-bind ((name &key namespace) &body body) args
 149     (multiple-value-bind (name-thunk constant-name-p)
 150         (compile-avt name env)
 151       (multiple-value-bind (ns-thunk constant-ns-p)
 152           (if namespace
 153               (compile-avt namespace env)
 154               (values nil t))
 155         (let ((value-thunk (compile-instruction `(progn ,@body) env)))
 156           (if (and constant-name-p constant-ns-p)
 157               (compile-attribute/constant-name name namespace env value-thunk)
 158               (compile-attribute/runtime name-thunk ns-thunk value-thunk)))))))
 159
 160 (defun compile-attribute/constant-name (qname namespace env value-thunk)
 161   ;; the simple case: compile-time decoding of the QName
 162   (multiple-value-bind (local-name uri prefix)
 163       (decode-qname qname env nil)
 164     (when namespace
 165       (setf uri namespace))
 166     (lambda (ctx)
 167       (write-attribute local-name
 168                        uri
 169                        (with-text-output-sink (s)
 170                          (with-xml-output s
 171                            (funcall value-thunk ctx)))
 172                        :suggested-prefix prefix))))
 173
 174 (defun compile-attribute/runtime (name-thunk ns-thunk value-thunk)
 175   ;; run-time decoding of the QName, but using the same namespaces
 176   ;; that would have been known at compilation time.
 177   (let ((namespaces *namespaces*))
 178     (lambda (ctx)
 179       (let ((qname (funcall name-thunk ctx)))
 180         (multiple-value-bind (local-name uri prefix)
 181             (decode-qname/runtime qname namespaces nil)
 182           (when ns-thunk
 183             (setf uri (funcall ns-thunk ctx)))
 184           (write-attribute local-name
 185                            (or uri "")
 186                            (with-text-output-sink (s)
 187                              (with-xml-output s
 188                                (funcall value-thunk ctx)))
 189                            :suggested-prefix prefix))))))
 190
 191 (defun remove-excluded-namespaces
 192     (namespaces &optional (excluded-uris *excluded-namespaces*))
 193   (let ((koerbchen '())
 194         (kroepfchen '()))
 195     (loop
 196        for cons in namespaces
 197        for (prefix . uri) = cons
 198        do
 199          (cond
 200            ((find prefix kroepfchen :test #'equal))
 201            ((find uri excluded-uris :test #'equal)
 202             (push prefix kroepfchen))
 203            (t
 204             (push cons koerbchen))))
 205     koerbchen))
 206
 207 (define-instruction xsl:literal-element (args env)
 208   (destructuring-bind
 209         ((local-name &optional (uri "") suggested-prefix) &body body)
 210       args
 211     (let ((body-thunk (compile-instruction `(progn ,@body) env))
 212           (namespaces (remove-excluded-namespaces *namespaces*)))
 213       (lambda (ctx)
 214         (with-element (local-name uri
 215                                   :suggested-prefix suggested-prefix
 216                                   :extra-namespaces namespaces)
 217           (funcall body-thunk ctx))))))
 218
 219 (define-instruction xsl:literal-attribute (args env)
 220   (destructuring-bind ((local-name &optional uri suggested-prefix) value) args
 221     (let ((value-thunk (compile-avt value env)))
 222       (lambda (ctx)
 223         (write-attribute local-name
 224                          uri
 225                          (funcall value-thunk ctx)
 226                          :suggested-prefix suggested-prefix)))))
 227
 228 (define-instruction xsl:text (args env)
 229   (destructuring-bind (str) args
 230     (lambda (ctx)
 231       (declare (ignore ctx))
 232       (write-text str))))
 233
 234 (define-instruction xsl:processing-instruction (args env)
 235   (destructuring-bind (name &rest body) args
 236     (let ((name-thunk (compile-avt name env))
 237           (value-thunk (compile-instruction `(progn ,@body) env)))
 238       (lambda (ctx)
 239         (write-processing-instruction
 240          (funcall name-thunk ctx)
 241          (with-text-output-sink (s)
 242            (with-xml-output s
 243              (funcall value-thunk ctx))))))))
 244
 245 (define-instruction xsl:comment (args env)
 246   (destructuring-bind (str) args
 247     (lambda (ctx)
 248       (declare (ignore ctx))
 249       (write-comment str))))
 250
 251 (define-instruction xsl:value-of (args env)
 252   (destructuring-bind (xpath) args
 253     (let ((thunk (compile-xpath xpath env)))
 254       (xslt-trace-thunk
 255        (lambda (ctx)
 256          (write-text (xpath:string-value (funcall thunk ctx))))
 257        "value-of ~s = ~s" xpath :result))))
 258
 259 (define-instruction xsl:unescaped-value-of (args env)
 260   (destructuring-bind (xpath) args
 261     (let ((thunk (compile-xpath xpath env)))
 262       (lambda (ctx)
 263         (write-unescaped (xpath:string-value (funcall thunk ctx)))))))
 264
 265 (define-instruction xsl:copy-of (args env)
 266   (destructuring-bind (xpath) args
 267     (let ((thunk (compile-xpath xpath env))
 268           ;; FIXME: what was this for?  --david
 269           #+(or) (v (intern-variable "varName" "")))
 270       (lambda (ctx)
 271         (let ((result (funcall thunk ctx)))
 272           (typecase result
 273             (xpath:node-set ;; FIXME: variables can contain node sets w/fragments inside. Maybe just fragments would do?
 274              (xpath:map-node-set #'copy-into-result result))
 275             (result-tree-fragment
 276              (copy-into-result result))
 277             (t
 278              (write-text (xpath:string-value result)))))))))
 279
 280 (defun copy-into-result (node)
 281   (cond
 282     ((result-tree-fragment-p node)
 283      (stp:do-children (child (result-tree-fragment-node node))
 284        (copy-into-result child)))
 285     ((xpath-protocol:node-type-p node :element)
 286      (with-element ((xpath-protocol:local-name node)
 287                     (xpath-protocol:namespace-uri node)
 288                     :suggested-prefix (xpath-protocol:namespace-prefix node)
 289                     ;; FIXME: is remove-excluded-namespaces correct here?
 290                     :extra-namespaces (remove-excluded-namespaces
 291                                        (namespaces-as-alist node)))
 292        (map-pipe-eagerly #'copy-into-result
 293                          (xpath-protocol:attribute-pipe node))
 294        (map-pipe-eagerly #'copy-into-result
 295                          (xpath-protocol:child-pipe node))))
 296     ((xpath-protocol:node-type-p node :document)
 297      (map-pipe-eagerly #'copy-into-result
 298                        (xpath-protocol:child-pipe node)))
 299     (t
 300      (copy-leaf-node node))))
 301
 302 (defun make-sorter (spec env)
 303   (destructuring-bind (&key select lang data-type order case-order)
 304       (cdr spec)
 305     ;; FIXME: implement case-order
 306     (declare (ignore lang case-order))
 307     (let ((select-thunk (compile-xpath (or select ".") env))
 308           (numberp (equal data-type "number"))
 309           (f (if (equal order "descending") -1 1)))
 310       (lambda (a b)
 311         (let ((i (xpath:string-value
 312                   (funcall select-thunk (xpath:make-context a))))
 313               (j (xpath:string-value
 314                   (funcall select-thunk (xpath:make-context b)))))
 315           (* f
 316              (if numberp
 317                  (signum (- (xpath:number-value i) (xpath:number-value j)))
 318                  (cond
 319                    ((string< i j) -1)
 320                    ((equal i j) 0)
 321                    (t 1)))))))))
 322
 323 (defun compose-sorters (sorters)
 324   (if sorters
 325       (let ((this (car sorters))
 326             (next (compose-sorters (rest sorters))))
 327         (lambda (a b)
 328           (let ((d (funcall this a b)))
 329             (if (zerop d)
 330                 (funcall next a b)
 331                 d))))
 332       (constantly 0)))
 333
 334 (defun make-sort-predicate (decls env)
 335   (let ((sorter
 336          (compose-sorters
 337           (mapcar (lambda (x) (make-sorter x env)) decls))))
 338     (lambda (a b)
 339       (minusp (funcall sorter a b)))))
 340
 341 (define-instruction xsl:for-each (args env)
 342   (destructuring-bind (select &optional decls &rest body) args
 343     (unless (and (consp decls)
 344                  (eq (car decls) 'declare))
 345       (push decls body)
 346       (setf decls nil))
 347     (let ((select-thunk (compile-xpath select env))
 348           (body-thunk (compile-instruction `(progn ,@body) env))
 349           (sort-predicate
 350            (when (cdr decls)
 351              (make-sort-predicate (cdr decls) env))))
 352       (lambda (ctx)
 353         (let ((selected (funcall select-thunk ctx)))
 354           (unless (xpath:node-set-p selected)
 355             (xslt-error "for-each select expression should yield a node-set"))
 356           (let ((nodes (xpath::force
 357                         (xpath::sorted-pipe-of selected))))
 358             (when sort-predicate
 359               (setf nodes (sort (copy-list nodes) sort-predicate)))
 360             (loop
 361               with n = (length nodes)
 362               for node in nodes
 363               for i from 1
 364               do
 365            (funcall body-thunk
 366                     (xpath:make-context node (lambda () n) i)))))))))
 367
 368 (define-instruction xsl:with-namespaces (args env)
 369   (destructuring-bind ((&rest forms) &rest body) args
 370     (let ((*namespaces* *namespaces*))
 371       (dolist (form forms)
 372         (destructuring-bind (prefix uri) form
 373           (push (cons prefix uri) *namespaces*)))
 374       (compile-instruction `(progn ,@body) env))))
 375
 376 (define-instruction xsl:with-excluded-namespaces (args env)
 377   (destructuring-bind ((&rest uris) &rest body) args
 378     (let ((*excluded-namespaces* (append uris *excluded-namespaces*)))
 379       (compile-instruction `(progn ,@body) env))))
 380
 381 ;; XSLT disallows multiple definitions of the same variable within a
 382 ;; template.  Local variables can shadow global variables though.
 383 ;; Since our LET syntax makes it natural to shadow local variables the
 384 ;; Lisp way, we check for duplicate variables only where instructed to
 385 ;; by the XML syntax parser using WITH-DUPLICATES-CHECK:
 386 (defvar *template-variables* nil)
 387
 388 (define-instruction xsl:with-duplicates-check (args env)
 389   (let ((*template-variables* *template-variables*))
 390     (destructuring-bind ((&rest qnames) &rest body) args
 391       (dolist (qname qnames)
 392         (multiple-value-bind (local-name uri)
 393             (decode-qname qname env nil)
 394           (let ((key (cons local-name uri)))
 395             (when (find key *template-variables* :test #'equal)
 396               (xslt-error "duplicate variable: ~A, ~A" local-name uri))
 397             (push key *template-variables*))))
 398       (compile-instruction `(progn ,@body) env))))
 399
 400 (define-instruction xsl:with-base-uri (args env)
 401   (destructuring-bind (uri &rest body) args
 402     (let ((*instruction-base-uri* uri))
 403       (compile-instruction `(progn ,@body) env))))
 404
 405 (defstruct (result-tree-fragment
 406              (:constructor make-result-tree-fragment (node)))
 407   node)
 408
 409 (define-default-method xpath-protocol:node-p
 410     ((node result-tree-fragment))
 411   t)
 412
 413 (define-default-method xpath-protocol:string-value
 414     ((node result-tree-fragment))
 415   (xpath-protocol:string-value (result-tree-fragment-node node)))
 416
 417 (defun apply-to-result-tree-fragment (ctx thunk)
 418   (let ((document
 419          (with-xml-output (stp:make-builder)
 420            (with-element ("fragment" "")
 421              (funcall thunk ctx)))))
 422     (make-result-tree-fragment (stp:document-element document))))
 423
 424 (define-instruction let (args env)
 425   (destructuring-bind ((&rest forms) &rest body) args
 426     (let* ((old-top (length *lexical-variable-declarations*))
 427            (vars-and-names (compile-var-bindings/nointern forms env))
 428            (vars-and-positions
 429             (loop for ((local-name . uri) thunk) in vars-and-names
 430                collect
 431                  (list (push-variable local-name
 432                                       uri
 433                                       *lexical-variable-declarations*)
 434                        thunk))))
 435       (let ((thunk (compile-instruction `(progn ,@body) env)))
 436         (fill *lexical-variable-declarations* nil :start old-top)
 437         (lambda (ctx)
 438           (loop for (index var-thunk) in vars-and-positions
 439              do (setf (lexical-variable-value index)
 440                       (funcall var-thunk ctx)))
 441           (funcall thunk ctx))))))
 442
 443 (define-instruction let* (args env)
 444   (destructuring-bind ((&rest forms) &rest body) args
 445     (if forms
 446         (compile-instruction `(let (,(car forms))
 447                                 (let* (,@(cdr forms))
 448                                   ,@body))
 449                              env)
 450         (compile-instruction `(progn ,@body) env))))
 451
 452 (define-instruction xsl:message (args env)
 453   (compile-message #'warn args env))
 454
 455 (define-instruction xsl:terminate (args env)
 456   (compile-message #'error args env))
 457
 458 (defun namespaces-as-alist (element)
 459   (let ((namespaces '()))
 460     (do-pipe (ns (xpath-protocol:namespace-pipe element))
 461       (push (cons (xpath-protocol:local-name ns)
 462                   (xpath-protocol:namespace-uri ns))
 463             namespaces))
 464     namespaces))
 465
 466 (define-instruction xsl:copy (args env)
 467   (let ((body (compile-instruction `(progn ,@args) env)))
 468     (lambda (ctx)
 469       (let ((node (xpath:context-node ctx)))
 470         (cond
 471           ((xpath-protocol:node-type-p node :element)
 472            (with-element
 473                ((xpath-protocol:local-name node)
 474                 (xpath-protocol:namespace-uri node)
 475                 :suggested-prefix (xpath-protocol:namespace-prefix node)
 476                 :extra-namespaces (namespaces-as-alist node))
 477              (funcall body ctx)))
 478           ((xpath-protocol:node-type-p node :document)
 479            (funcall body ctx))
 480           (t
 481            (copy-leaf-node node)))))))
 482
 483 (defun copy-leaf-node (node)
 484   (cond
 485     ((xpath-protocol:node-type-p node :text)
 486      (write-text (xpath-protocol:string-value node)))
 487     ((xpath-protocol:node-type-p node :comment)
 488      (write-comment (xpath-protocol:string-value node)))
 489     ((xpath-protocol:node-type-p node :processing-instruction)
 490      (write-processing-instruction
 491          (xpath-protocol:processing-instruction-target node)
 492        (xpath-protocol:string-value node)))
 493     ((xpath-protocol:node-type-p node :attribute)
 494      (write-attribute
 495       (xpath-protocol:local-name node)
 496       (xpath-protocol:namespace-uri node)
 497       (xpath-protocol:string-value node)
 498       :suggested-prefix (xpath-protocol:namespace-prefix node)))
 499     (t
 500      (error "don't know how to copy node ~A" node))))
 501
 502 (defun compile-message (fn args env)
 503   (let ((thunk (compile-instruction `(progn ,@args) env)))
 504     (lambda (ctx)
 505       (funcall fn
 506                (with-xml-output (cxml:make-string-sink)
 507                  (funcall thunk ctx))))))
 508
 509 (define-instruction xsl:apply-templates (args env)
 510   (destructuring-bind ((&key select mode) &rest param-binding-specs) args
 511     (let* ((decls
 512             (when (and (consp (car param-binding-specs))
 513                        (eq (caar param-binding-specs) 'declare))
 514               (cdr (pop param-binding-specs))))
 515            (select-thunk
 516             (compile-xpath (or select "child::node()") env))
 517            (param-bindings
 518             (compile-var-bindings param-binding-specs env))
 519            (sort-predicate
 520             (when decls
 521               (make-sort-predicate decls env))))
 522       (multiple-value-bind (mode-local-name mode-uri)
 523           (and mode (decode-qname mode env nil))
 524         (lambda (ctx)
 525           (let ((*mode* (if mode
 526                             (or (find-mode *stylesheet*
 527                                            mode-local-name
 528                                            mode-uri)
 529                                 *empty-mode*)
 530                             *mode*)))
 531             (apply-templates/list
 532              (xpath::force
 533               (xpath::sorted-pipe-of (funcall select-thunk ctx)))
 534              (loop for (name nil value-thunk) in param-bindings
 535                 collect (list name (funcall value-thunk ctx)))
 536              sort-predicate)))))))
 537
 538 (define-instruction xsl:apply-imports (args env)
 539   (declare (ignore args env))
 540   (lambda (ctx)
 541     (declare (ignore ctx))
 542     (funcall *apply-imports*)))
 543
 544 (define-instruction xsl:call-template (args env)
 545   (destructuring-bind (name &rest param-binding-specs) args
 546       (let ((param-bindings
 547              (compile-var-bindings param-binding-specs env)))
 548         (multiple-value-bind (local-name uri)
 549             (decode-qname name env nil)
 550           (setf name (cons local-name uri)))
 551         (lambda (ctx)
 552           (call-template ctx name
 553                          (loop for (name nil value-thunk) in param-bindings
 554                                collect (list name (funcall value-thunk ctx))))))))
 555
 556 (defun compile-instruction (form env)
 557   (xslt-trace-thunk
 558    (funcall (or (get (car form) 'xslt-instruction)
 559                 (error "undefined instruction: ~A" (car form)))
 560             (cdr form)
 561             env)
 562    "instruction ~s" (car form)))
 563
 564 ;;: WTF: "A right curly brace inside a Literal in an expression is not
 565 ;;; recognized as terminating the expression."
 566 ;;;
 567 ;;; Da hilft nur tagbody.
 568 (defun parse-attribute-value-template (template-string)
 569   (with-input-from-string (input template-string)
 570     (let ((ordinary (make-string-output-stream))
 571           (xpath (make-string-output-stream))
 572           (tokens '())
 573           (c (read-char input nil :eof)))
 574       (flet ((emit ()
 575                (let ((o (get-output-stream-string ordinary)))
 576                  (when (plusp (length o))
 577                    (push (list :data o) tokens)))
 578                (let ((x (get-output-stream-string xpath)))
 579                  (when (plusp (length x))
 580                    (push (list :xpath x) tokens))))
 581              (collect-ordinary ()
 582                (write-char c ordinary))
 583              (collect-xpath ()
 584                (write-char c xpath)))
 585         (macrolet ((goto (target)
 586                      `(progn
 587                         (setf c (read-char input nil :eof))
 588                         (go ,target))))
 589           (tagbody
 590            ordinary
 591              (case c
 592                (#\{
 593                 (goto seen{))
 594                (#\}
 595                 (goto seen-stray-}))
 596                (:eof
 597                 (go done)))
 598              (collect-ordinary)
 599              (goto ordinary)
 600
 601            seen{
 602              (case c
 603                (#\{
 604                 (collect-ordinary)
 605                 (goto ordinary))
 606                (#\'
 607                 (collect-xpath)
 608                 (goto in-single-quote))
 609                (:eof
 610                 (xslt-error "unexpected end of avt")))
 611              (emit)
 612              (collect-xpath)
 613              (goto xpath)
 614
 615            xpath
 616              (case c
 617                (#\'
 618                 (collect-xpath)
 619                 (goto in-single-quote))
 620                (#\"
 621                 (collect-xpath)
 622                 (goto in-double-quote))
 623                (#\}
 624                 (goto seen-closing-}))
 625                (:eof
 626                 (xslt-error "unexpected end of avt")))
 627              (collect-xpath)
 628              (goto xpath)
 629
 630            in-single-quote
 631              (case c
 632                (#\'
 633                 (collect-xpath)
 634                 (goto xpath))
 635                (:eof
 636                 (xslt-error "unexpected end of avt")))
 637              (collect-xpath)
 638              (goto in-single-quote)
 639
 640            in-double-quote
 641              (case c
 642                (#\"
 643                 (collect-xpath)
 644                 (goto xpath))
 645                (:eof
 646                 (xslt-error "unexpected end of avt")))
 647              (collect-xpath)
 648              (goto in-double-quote)
 649
 650            seen-closing-}
 651              (case c
 652                (#\}
 653                 (collect-xpath)
 654                 (goto xpath))
 655                (#\{
 656                 (emit)
 657                 (goto xpath))
 658                (:eof
 659                 (goto done)))
 660              (emit)
 661              (collect-ordinary)
 662              (goto ordinary)
 663
 664            seen-stray-}
 665              (case c
 666                (#\}
 667                 (collect-ordinary)
 668                 (goto ordinary)))
 669              (xslt-error "unexpected closing brace in avt")
 670
 671            done
 672              (emit))))
 673       (nreverse tokens))))
 674
 675 (defun compile-avt (template-string env)
 676   (let* ((constantp t)
 677          (fns
 678           (mapcar (lambda (x)
 679                     (ecase (car x)
 680                       (:data
 681                        (constantly (second x)))
 682                       (:xpath
 683                        (setf constantp nil)
 684                        (compile-xpath (second x) env))))
 685                   (parse-attribute-value-template template-string))))
 686     (values (lambda (ctx)
 687               (with-output-to-string (s)
 688                 (dolist (fn fns)
 689                   (write-string (xpath:string-value (funcall fn ctx)) s))))
 690             constantp)))
 691
 692
 693 ;;;; Indentation for slime
 694
 695 (defmacro define-indentation (name (&rest args))
 696   (labels ((collect-variables (list)
 697              (loop
 698                 for sub in list
 699                 append
 700                 (etypecase sub
 701                   (list
 702                    (collect-variables sub))
 703                   (symbol
 704                    (if (eql (mismatch "&" (symbol-name sub)) 1)
 705                        nil
 706                        (list sub)))))))
 707     `(defmacro ,name (,@args)
 708        (declare (ignorable ,@(collect-variables args)))
 709        (error "XSL indentation helper ~A used literally in lisp code"
 710               ',name))))
 711
 712 (define-indentation xsl:element
 713     ((name &key namespace use-attribute-sets) &body body))
 714 (define-indentation xsl:literal-element ((name &optional uri) &body body))
 715 (define-indentation xsl:attribute ((name &key namespace) &body body))
 716 (define-indentation xsl:literal-attribute ((name &optional uri) &body body))
 717 (define-indentation xsl:text (str))
 718 (define-indentation xsl:processing-instruction (name &body body))
 719 (define-indentation xsl:comment (str))
 720 (define-indentation xsl:value-of (xpath))
 721 (define-indentation xsl:unescaped-value-of (xpath))
 722 (define-indentation xsl:for-each (select &body decls-and-body))
 723 (define-indentation xsl:message (&body body))
 724 (define-indentation xsl:terminate (&body body))
 725 (define-indentation xsl:apply-templates ((&key select mode) &body decls-and-body))
 726 (define-indentation xsl:call-template (name &rest parameters))
 727 (define-indentation xsl:copy-of (xpath))
 728
 729 ;;;;
 730
 731 (defun test-instruction (form document)
 732   (let ((thunk (compile-instruction form (make-instance 'lexical-environment)))
 733         (root (cxml:parse document (stp:make-builder))))
 734     (with-xml-output (cxml:make-string-sink)
 735       (funcall thunk (xpath:make-context root)))))