Support “soft” dependencies

[Shushe] / README.markdown

diff --git a/README.markdown b/README.markdown
index d4399e35a858c3b514e335e22a209150c60904b8..be400b9e2b9a4c9d9e24830dc5d53977e6fe7b0e 100644 (file)
--- a/README.markdown
+++ b/README.markdown
@@ -188,6 +188,7 @@ This document uses a few name·space prefixes, with the following
 |    `exsl:` | `http://exslt.org/common`                     |
 | `exslstr:` | `http://exslt.org/strings`                    |
 |    `html:` | `http://www.w3.org/1999/xhtml`                |
 |    `exsl:` | `http://exslt.org/common`                     |
 | `exslstr:` | `http://exslt.org/strings`                    |
 |    `html:` | `http://www.w3.org/1999/xhtml`                |

+|     `rdf:` | `http://www.w3.org/1999/02/22-rdf-syntax-ns#` |

 |     `svg:` | `http://www.w3.org/2000/svg`                  |
 |   `xlink:` | `http://www.w3.org/1999/xlink`                |
 |    `xslt:` | `http://www.w3.org/1999/XSL/Transform`        |
 |     `svg:` | `http://www.w3.org/2000/svg`                  |
 |   `xlink:` | `http://www.w3.org/1999/xlink`                |
 |    `xslt:` | `http://www.w3.org/1999/XSL/Transform`        |


@@ -307,6 +308,12 @@ The following additional variables can be used to control the behaviour
     default, to enable additional rules without overriding the existing
     ones.
 
     default, to enable additional rules without overriding the existing
     ones.
 

+- **`DATAOPTS`:**
+  Additional options to use when calling Make during the first stage of a two‐stage build using `DATADIR`.
+
+  This can be used to override variables which are only applicable during the second stage.
+  Note that when supplying this variable on the shell, it will need to be double‐quoted.
+

 - **`DATAEXT`:**
   A list of file extensions which signify “data” files during a two‐stage build using `DATADIR`.
 
 - **`DATAEXT`:**
   A list of file extensions which signify “data” files during a two‐stage build using `DATADIR`.
 


@@ -541,6 +548,18 @@ These include :⁠—
 - A `@书社:media-type` attribute, giving the identified media type of
     the plaintext node.
 
 - A `@书社:media-type` attribute, giving the identified media type of
     the plaintext node.
 

+### Parsed metadata
+
+It is possible to extract metadata from a document at the same time as
+  it is being parsed.
+This is done by creating result elements in the `书社:about` mode;
+  these should be R·D·F property elements which apply to the conceptual
+  entity that is the document being parsed.
+
+During transformation, metadata for the file with identifier `$FILE`
+  can be read from the children of
+  `$书社:about//*[@rdf:about=$FILE]/nie:interpretedAs/*`.
+

 ## Output Redirection
 
 By default, ⛩📰 书社 installs files to the same location in `DESTDIR`
 ## Output Redirection
 
 By default, ⛩📰 书社 installs files to the same location in `DESTDIR`


@@ -550,10 +569,14 @@ This behaviour can be customized by setting the `@书社:destination`
 This attribute is read after parsing, but before transformation (where
   it is silently dropped).
 
 This attribute is read after parsing, but before transformation (where
   it is silently dropped).
 

+Multiple destinations can be provided if the same file should be output to multiple places.
+The file is retransformed each time, with the value of the `DESTINATION` global param set appropriately.
+

 ## Embedding
 
 Documents can be embedded in other documents using a `<书社:link>`
 ## Embedding
 
 Documents can be embedded in other documents using a `<书社:link>`

-  element with `@xlink:show="embed"`.
+  element with `@xlink:show="embed"` and an `@xlink:actuate` which is
+  absent or `"none"`.

 The `@xlink:href`s of these elements should have the format
   `about:shushe?source=<path>`, where `<path>` provides the path to the
   file within `SRCDIR`.
 The `@xlink:href`s of these elements should have the format
   `about:shushe?source=<path>`, where `<path>` provides the path to the
   file within `SRCDIR`.


@@ -561,6 +584,8 @@ Includes, which do not generate outputs of their own but may still be
   freely embedded, instead use the format
   `about:shushe?include=<path>`, where `<path>` provides the path
   within `INCLUDEDIR`.
   freely embedded, instead use the format
   `about:shushe?include=<path>`, where `<path>` provides the path
   within `INCLUDEDIR`.

+If `<path>` indicates a directory and ends with a slash (`/`),
+  everything within that directory will be embedded.

 
 Embeds are replaced with the parsed contents of a file, unless the file
   is an asset, in which case an `<html:object>` element is produced
 
 Embeds are replaced with the parsed contents of a file, unless the file
   is an asset, in which case an `<html:object>` element is produced


@@ -600,6 +625,40 @@ These include :⁠—
   These attributes are used to scope any nested `<html:meta>` elements
     with `@itemprop` attributes to their containing documents.
 
   These attributes are used to scope any nested `<html:meta>` elements
     with `@itemprop` attributes to their containing documents.
 

+## Soft Dependencies
+
+When a file depends only on the metadata of another file, and not its
+  contents, it can be added as a soft dependency rather than an embed.
+Soft dependencies are indicated using a `<书社:link>` element with an
+  `@xlink:show` of `"other"`, `"none"`, or absent, and an
+  `@xlink:actuate` which is absent or `"none"`.
+A change to a soft dependency requires a file to be rebuilt, but no
+  embedding occurs automatically.
+Because there is no automatic embedding, soft dependencies are allowed
+  to be recursive.
+
+The `@xlink:href`s of soft dependency `<书社:link>`s are processed in
+  exactly the same fashion as embeds, described above.
+
+If the value of `@xlink:show` is `"other"`, the soft dependency is
+  transitive.
+Any dependencies of the indicated file which have a `@name` which
+  matches that of the referencing `<书社:link>` element will also be
+  treated as soft dependencies.
+If no `@name` is given, it is treated as the empty string.
+
+When a document is embedded directly, all of its soft dependencies are
+  also treated as soft dependencies of the embedding object.
+However, a document is embedded in a transitive soft dependency, the
+  embed is treated exactly as tho it were itself a transitive soft
+  dependency.
+That means it must have a matching `@name` to be included, and
+  like·wise for any embeds or soft dependencies it contains.
+
+If the value of `@xlink:show` is `"none"` or absent, the soft
+  dependency is not transitive and its own dependencies are not
+  checked.
+

 ## Transforms
 
 Transforms are used to convert X·M·L files into their final output,
 ## Transforms
 
 Transforms are used to convert X·M·L files into their final output,


@@ -614,6 +673,9 @@ Transforms are used to convert X·M·L files into their final output,
   This conversion happens during the finalization phase, after the main
     transformation.
 
   This conversion happens during the finalization phase, after the main
     transformation.
 

+- **`transforms/expansion.xslt`:**
+  Performs embedding, as described above.
+

 - **`transforms/metadata.xslt`:**
   Provides basic `<html:head>` metadata.
   This metadata is generated from `<html:meta>` elements with one of
 - **`transforms/metadata.xslt`:**
   Provides basic `<html:head>` metadata.
   This metadata is generated from `<html:meta>` elements with one of


@@ -684,6 +746,28 @@ The following params are made available globally in parsers and
 - **`THISREV`:**
   The value of the `THISREV` variable (if present).
 
 - **`THISREV`:**
   The value of the `THISREV` variable (if present).
 

+In transforms, the following params are additionally available :⁠—
+
+- **`DESTINATION`:**
+  The destination being targeted by this transform.
+
+- **`书社:about`:**
+  R·D·F metadata about all of the documents ⛩📰 书社 knows about.
+  Use `$书社:about//*[@rdf:about=$IDENTIFIER]` to get the metadata for
+    the current document.
+
+- **`书社:source`:**
+  The parsed source document being transformed, prior to any expansion.
+
+- **`书社:expansion`:**
+  The document after the all embeds have been expanded.
+  Unavailable during the `书社:expand` stage.
+
+- **`书社:result`:**
+  The document after the main set of transformations have been applied.
+  Only available during the `书社:finalize` stage, where it is used to
+    apply output wrapping and other clean·up.
+

 ## Output Wrapping
 
 Provided at least one toplevel result element belongs to the H·T·M·L
 ## Output Wrapping
 
 Provided at least one toplevel result element belongs to the H·T·M·L