Implement the lexer, parser, and expander for a core subset of JSON Template.

3 files changed, 375 insertions, 0 deletions

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/json-template.asd b/json-template.asd
new file mode 100644
index 0000000..39f94dc
--- /dev/null
+++ b/json-template.asd
@@ -0,0 +1,23 @@
+;; -*- mode: lisp; coding: utf-8 -*-
+;;
+;; Copyright 2011, Matthias Andreas Benkard.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;;     http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+
+
+(asdf:defsystem json-template
+  :author "Matthias Andreas Benkard"
+  :description "An implementation of a subset of the JSON Template language."
+  :license "Apache License, version 2.0"
+  :version "0.1.0"
+  :components ((:file "json-template")))
diff --git a/json-template.lisp b/json-template.lisp
new file mode 100644
index 0000000..59e1265
--- /dev/null
+++ b/json-template.lisp
@@ -0,0 +1,150 @@
+;; -*- mode: lisp; coding: utf-8 -*-
+;;
+;; Copyright 2011, Matthias Andreas Benkard.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;;     http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+
+
+(defpackage #:json-template
+  (:use #:common-lisp)
+  (:export #:parse-template-string
+           #:expand-template
+           #:*template-filters*))
+
+(in-package #:json-template)
+
+
+(defvar *template-filters*
+    `(;;("html"            . filter-html)
+      ;;("html-attr-value" . filter-html-attr-value)
+      ("raw"             . identity)))
+
+(defun tokenize-template-string (string)
+  (loop with in-command-p = nil
+        with position = 0
+        for terminator = (position (if in-command-p #\} #\{) string
+                                   :start position)
+        collect (cons in-command-p
+                      (subseq string
+                              position
+                              (or terminator (length string))))
+        do (setq position (and terminator (1+ terminator))
+                 in-command-p (not in-command-p))
+        until (null terminator)))
+
+(defun parse-template-string (stream)
+  (parse-raw-tokens (tokenize-template-string stream)))
+
+(defun parse-directive (string)
+  (let* ((space1 (position #\Space string))
+         (space2 (and space1 (position #\Space string :start (1+ space1)))))
+    (list (intern (string-upcase (subseq string 1 (or space1 (length string))))
+                  '#:keyword)
+          (if space1
+              (subseq string (1+ space1) (or space2 (length string)))
+              nil)
+          (if space2
+              (subseq string (1+ space2))
+              nil))))
+
+(defun parse-variable (string)
+  (let ((pipe (position #\| string)))
+    (if pipe
+        (list (subseq string 0 pipe)
+              (subseq string (1+ pipe)))
+        (list string nil))))
+
+(defun parse-token (token)
+  (destructuring-bind (command-p . data)
+      token
+    (if command-p
+        (if (char= (char data 0) #\.)
+            (list* :directive (parse-directive data))
+            (list* :variable (parse-variable data)))
+        (list :text data))))
+
+(defun parse-raw-tokens (tokens)
+  (parse-tokens (mapcar #'parse-token tokens)))
+
+(defun parse-tokens (tokens)
+  (let ((result (loop for token = (and tokens (car tokens))
+                      for token-kind = (first token)
+                      for token-data = (rest token)
+                      until (or (null tokens)
+                                (and (eq token-kind :directive)
+                                     (member (second token) '(:or :end))))
+                      do (setq tokens (cdr tokens))
+                      if (eq token-kind :directive)
+                        collect (multiple-value-bind (subresult rest-tokens)
+                                    (parse-tokens tokens)
+                                  (let ((sub-end-tag (first rest-tokens)))
+                                    (setq tokens (rest rest-tokens))
+                                    (let ((alternative
+                                           (and (equal sub-end-tag '(:directive :or nil nil))
+                                                (multiple-value-bind (altresult rest-tokens2)
+                                                    (parse-tokens tokens)
+                                                  (setq tokens (rest rest-tokens2))
+                                                  altresult))))
+                                      (ecase (first token-data)
+                                        (:section
+                                         (list :section
+                                               (second token-data)
+                                               subresult
+                                               alternative))
+                                        (:repeated
+                                         (list :repeated-section
+                                               (third token-data)
+                                               subresult
+                                               alternative))))))
+                      else if (member token-kind '(:variable :text))
+                        collect token
+                      else do (error "Encountered invalid token: ~S" token))))
+    (values result tokens)))
+
+(defun expand-template (template context)
+  (with-output-to-string (out)
+    (expand-template-to-stream template context out)))
+
+(defun expand-template-to-stream (template context stream)
+  (dolist (thing template)
+    (ecase (first thing)
+      (:text
+       (write-string (second thing) stream))
+      (:variable
+       (destructuring-bind (variable filter) (cdr thing)
+         (let ((value (getf context
+                            (intern (string-upcase variable)
+                                    '#:keyword)
+                            nil)))
+           (format stream "~A"
+                   (if filter
+                       (funcall (cdr (assoc filter *template-filters*))
+                                value)
+                       value)))))
+      (:section
+       (destructuring-bind (section branch alternative) (cdr thing)
+         (let ((value (getf context (intern (string-upcase section) '#:keyword) nil)))
+           (expand-template-to-stream (if value branch alternative)
+                                      value
+                                      stream))))
+      (:repeated-section
+       (destructuring-bind (section branch alternative) (cdr thing)
+         (let ((value (if (string= section "@")
+                          context
+                          (getf context (intern (string-upcase section) '#:keyword)
+                                nil))))
+           (if value
+               (mapc (lambda (ctx)
+                       (expand-template-to-stream branch ctx stream))
+                     value)
+               (expand-template-to-stream alternative value stream))))))))