Text.Pandoc.Shared: add parameter to uniqueIdent, inlineListToIdentifier.

The parameter is Extensions. This allows these functions to
be sensitive to the settings of `Ext_gfm_auto_identifiers` and
`Ext_ascii_identifiers`.

This allows us to use `uniqueIdent` in the CommonMark reader,
replacing some custom code.

It also means that `gfm_auto_identifiers` can now be used
in all formats.

Semantically, `gfm_auto_identifiers` is now a modifier of
`auto_identifiers`; for identifiers to be set, `auto_identifiers`
must be turned on, and then the type of identifier produced
depends on `gfm_auto_identifiers` and `ascii_identifiers` are set.

Closes #5057.

1 files changed, 24 insertions, 9 deletions

diff --git a/MANUAL.txt b/MANUAL.txt
index 726219b1b..d712ae998 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -1852,7 +1852,8 @@ output formats
 enabled by default in
 :  `markdown`, `muse`
 
-The algorithm used to derive the identifier from the header text is:
+The default algorithm used to derive the identifier from the
+header text is:
 
   - Remove all formatting, links, etc.
   - Remove all footnotes.
@@ -1879,6 +1880,9 @@ same text; in this case, the first will get an identifier as described
 above; the second will get the same identifier with `-1` appended; the
 third with `-2`; and so on.
 
+(However, a different algorithm is used if
+`gfm_auto_identifiers` is enabled; see below.)
+
 These identifiers are used to provide link targets in the table of
 contents generated by the `--toc|--table-of-contents` option. They
 also make it easy to provide links from one section of a document to
@@ -1903,6 +1907,13 @@ Causes the identifiers produced by `auto_identifiers` to be pure ASCII.
 Accents are stripped off of accented Latin letters, and non-Latin
 letters are omitted.
 
+#### Extension: `gfm_auto_identifiers` ####
+
+Changes the algorithm used by `auto_identifiers` to conform to
+GitHub's method.  Spaces are converted to dashes (`-`),
+uppercase characters to lowercase characters, and punctuation
+characters other than `-` and `_` are removed.
+
 Math Input
 ----------
 
@@ -4189,10 +4200,11 @@ variants are supported:
     `shortcut_reference_links`, `spaced_reference_links`.
 
 `markdown_github` (deprecated GitHub-Flavored Markdown)
-:   `pipe_tables`, `raw_html`, `fenced_code_blocks`, `gfm_auto_identifiers`,
-    `ascii_identifiers`, `backtick_code_blocks`, `autolink_bare_uris`,
-    `space_in_atx_header`, `intraword_underscores`, `strikeout`,
-    `emoji`, `shortcut_reference_links`, `angle_brackets_escapable`,
+:   `pipe_tables`, `raw_html`, `fenced_code_blocks`, `auto_identifiers`,
+    `gfm_auto_identifiers`, `backtick_code_blocks`,
+    `autolink_bare_uris`, `space_in_atx_header`,
+    `intraword_underscores`, `strikeout`, `emoji`,
+    `shortcut_reference_links`, `angle_brackets_escapable`,
     `lists_without_preceding_blankline`.
 
 `markdown_mmd` (MultiMarkdown)
@@ -4219,10 +4231,13 @@ individually disabled.
 Also, `raw_tex` only affects `gfm` output, not input.
 
 `gfm` (GitHub-Flavored Markdown)
-:   `pipe_tables`, `raw_html`, `fenced_code_blocks`, `gfm_auto_identifiers`,
-    `backtick_code_blocks`, `autolink_bare_uris`,
-    `intraword_underscores`, `strikeout`, `hard_line_breaks`, `emoji`,
-    `shortcut_reference_links`, `angle_brackets_escapable`.
+:   `pipe_tables`, `raw_html`, `fenced_code_blocks`, `auto_identifiers`,
+    `gfm_auto_identifiers`, `backtick_code_blocks`,
+    `autolink_bare_uris`, `space_in_atx_header`,
+    `intraword_underscores`, `strikeout`, `emoji`,
+    `shortcut_reference_links`, `angle_brackets_escapable`,
+    `lists_without_preceding_blankline`.
+
 
 Producing slide shows with pandoc
 =================================