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