120 lines
3.5 KiB
Markdown
120 lines
3.5 KiB
Markdown
# libhl
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## API
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```C
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int hl_init(void);
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int hl_deinit(void);
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```
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These functions are responsible for the library's "life time".
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`hl_init()` must be called before any other library function.
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`hl_deinit()` will ensure all occupied memory is freed.
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```C
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void render_string(const char * const string, const char * const mode);
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```
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This function matches _string_ against all known highlighting rules and dispatches the appropriate callback depending on _mode_.
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```C
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#define HLPATH //?!
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```
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Coma separated list of directories to be searched for syntax scripts. `#undef` to disable it entirely.
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```C
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typedef void (*attribute_callback_t)(const char * const string, const int length, void * const attributes);
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```
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The type used for defining appropriate callbacks for render_string().
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+ string - string to be outputed
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+ length - number of characters that matched a highlighting rule
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+ attributes - arbitrary data associated with the matched rule; intended to hold color/font information for example
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```C
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typedef struct {
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char * key;
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attribute_callback_t callback;
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} display_t;
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```
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The type for defining display modes.
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void new_display_mode(display_t * mode);
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This is how you append a display mode that render_string() will search based on _.key_.
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```C
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typedef enum {
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KEYSYMBOL,
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KEYWORD,
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MATCH,
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REGION
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} token_type_t;
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```
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These are the valid type of distinct token types.
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+ KEYSYMBOL - a string which is contextless, the surounding text is ignored
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"mysymbol" will match inside all of these:
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"something mysymbol something"
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"somethingmysymbolsomething"
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it is intended to match such thing as programming language operators
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+ KEYWORD - a string which is recognized when surounded by word bundaries such as ' ' or '\t'
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+ MATCH - a regular expression to be recognized
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+ REGION - a regular expression where the starting and ending patters are to be distinguished from the contents
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The universal way to add a new pattern to be recognized is with:
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```C
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token * new_token(const char * const syntax, const token_type_t t, const hl_group_t * const g);
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```
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There are also convinience functions:
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```C
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// NOTE: the return value is the number tokens successfully inserted
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int new_keyword_tokens(const char * const * words, hl_group_t * const g); // _words_ must be NULL terminated
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int new_syntax_character_tokens(const char * const chars, hl_group_t * const g);
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```
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The regex engine used for MATCHes is Jeger by default, emulating Vim regex.
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However the regex engine can be overridden:
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```C
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// ?!
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```
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---
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# hl
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General purpose highlighter (and demo program for libhl).
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## Usage
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hl will read from stdin and write to stdout.
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```bash
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hl < source/main.c
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```
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### Cli Options
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```bash
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-h : display help message
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-I <dir> : syntax file look up directory
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-s <syntax> : specify syntax to load
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```
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### Environment variables
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```bash
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$HLPATH : colon separated list of directories searched for syntax script files;
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overriddes the value of the HLPATH macro
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```
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---
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# Scripting
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hl can parse a small subset of VimScript: the few instructions related to highlighing, and it ignores everything else.
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All Vim highlighing scripts should be valid hl scripts.
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The instrunctions in particular are:
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```vimscript
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sy[ntax] keyword <hl_group> <word>+
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sy[ntax] match <hl_group> <regex>
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sy[ntax] region <hl_group> start=<string|match> end=<string|match>
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hi[ghtlight] link <from_group> <to_group>
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hi[ghtlight] def <group> <display_t>=<data>+
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```
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Additionally hl recognizes:
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```vimscript
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syn[ntax] keysymbol <char>+
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```
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