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@@ -55,20 +55,38 @@
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 Hacking
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 =======
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-It should be pretty easy to modify markdown.leg to produce other formats
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+It should be pretty easy to modify the program to produce other formats
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 than HTML or LaTeX, and to parse syntax extensions.  A quick guide:
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-  * To add an output format, add the format to 'formats', modify 'print_element',
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-    and add functions corresponding to 'print_html_string', 'print_html_element',
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-    and 'print_html_element_list'.  Also add an option in the main loop that selects
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-    the new format.
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+  * `markdown_peg.h` contains declarations for both `markdown_parser.leg`
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+    and `markdown_output.c`.
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+  * `markdown_parser.leg` contains the grammar itself, the `markdown()`
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+    function, and some utility functions used by the parser actions.
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+
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+  * `markdown_output.c` contains functions for printing the `Element`
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+    structure in various output formats.  (This includes calling
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+    `markdown()` again when needed to parse list items and blockquotes,
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+    which are stored initially as raw strings.)
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+
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+  * To add an output format, add the format to `formats`, modify
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+    `print_element`, and add functions `print_XXXX_string`,
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+    `print_XXXX_element`, and `print_XXXX_element_list`. Also add an
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+    option in the main program that selects the new format. Don't forget
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+    to add it to the help message.
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+
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   * To add syntax extensions, define them in the PEG grammar (bottom part
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-    of markdown.leg), using existing definitions as a guide. If you need
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-    to add new types of elements (e.g. FOOTNOTE), modify the 'keys'
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-    enum.  By using `&{ }` rules it should be possible to selectively
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-    disable extensions depending on command-line options.
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+    of `markdown_parser.leg`), using existing definitions as a guide.
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+    New inline elements will need to be added to `Inline =`; new block
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+    elements will need to be added to `Block =`. If you need to add new
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+    types of elements (e.g. `FOOTNOTE`), modify the `keys` enum. By using
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+    `&{ }` rules one can selectively disable extensions depending
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+    on command-line options. For example, `&{ (syntax_extensions &
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+    EXT_SMART) }` succeeds only if the `EXT_SMART` bit of the global
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+    syntax_extensions is set.  Add your option to `markdown_extensions`,
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+    and modify the option parsing in markdown.c so that your option gets
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+    set appropriately.
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-  * Note:  Avoid using [^abc] character classes in the grammar, because they
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-    cause problems with non-ascii input.  Instead, use:  ( !'a' !'b' !'c' . )
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+  * Note:  Avoid using `[^abc]` character classes in the grammar, because they
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+    cause problems with non-ascii input.  Instead, use:  `( !'a' !'b' !'c' . )`