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libpsyc/include/psyc/text.h
2011-11-01 12:06:58 +01:00

156 lines
4.9 KiB
C

#ifndef PSYC_TEXT_H
/**
* @file psyc/text.h
* @brief Interface for text template rendering.
*
* All text template functions and the definitions they use are
* defined in this file.
*/
/**
* @defgroup text Text template functions
*
* This module contains all text template functions.
* @{
*/
/**
* Return values for the text template parsing function.
* @see psyc_text()
*/
typedef enum
{
/// No substitution was made, nothing was written to the buffer.
PSYC_TEXT_NO_SUBST = -1,
/// Text template parsing & rendering complete.
PSYC_TEXT_COMPLETE = 0,
/// Text template parsing & rendering is incomplete, because the buffer was too small.
/// Another call is required to this function after setting a new buffer.
PSYC_TEXT_INCOMPLETE = 1,
} PsycTextRC;
/**
* Return values for PsycTextCB.
*/
typedef enum
{
/// Value not found, don't substitute anything.
PSYC_TEXT_VALUE_NOT_FOUND = -1,
/// Value found, substitute contents of the value variable.
PSYC_TEXT_VALUE_FOUND = 0,
} PsycTextValueRC;
/**
* Struct for keeping PSYC text parser state.
*/
typedef struct
{
size_t cursor; ///< current position in the template
size_t written; ///< number of bytes written to buffer
PsycString tmpl; ///< input buffer with text template to parse
PsycString buffer; ///< output buffer for rendered text
PsycString open;
PsycString close;
} PsycTextState;
/**
* Callback for psyc_text() that produces a value for a match.
*
* The application looks up a match such as _fruit from [_fruit] and
* if found sets value->data & value->length to point to the found value,
* "Apple" for example. 0 is a legal value for the length.
* The callbacks returns either PSYC_TEXT_VALUE_FOUND or
* PSYC_TEXT_VALUE_NOT_FOUND if no match found in which case psyc_text
* leaves the original template text as is.
*/
typedef PsycTextValueRC (*PsycTextCB)(const char *name, size_t len, PsycString *value, void *extra);
/**
* Initializes the PSYC text state struct.
*
* @param state Pointer to the PSYC text state struct that should be initialized.
* @param tmpl Input buffer with text template to be parsed.
* @param tmplen Length of input buffer.
* @param buffer Output buffer where the rendered text is going to be written.
* @param buflen Length of output buffer.
*/
static inline
void psyc_text_state_init (PsycTextState *state,
char *tmpl, size_t tmplen,
char *buffer, size_t buflen)
{
state->cursor = 0;
state->written = 0;
state->tmpl = (PsycString) {tmplen, tmpl};
state->buffer = (PsycString) {buflen, buffer};
state->open = (PsycString) {1, "["};
state->close = (PsycString) {1, "]"};
}
/**
* Initializes the PSYC text state struct with custom opening & closing braces.
*
* @param state Pointer to the PSYC text state struct that should be initialized.
* @param tmpl Input buffer with text template to be parsed.
* @param tmplen Length of input buffer.
* @param buffer Output buffer where the rendered text is going to be written.
* @param buflen Length of output buffer.
* @param open Opening brace.
* @param openlen Length of opening brace.
* @param close Closing brace.
* @param closelen Length of closing brace.
*/
static inline
void psyc_text_state_init_custom (PsycTextState *state,
char *tmpl, size_t tmplen,
char *buffer, size_t buflen,
char *open, size_t openlen,
char *close, size_t closelen)
{
state->cursor = 0;
state->written = 0;
state->tmpl = (PsycString) {tmplen, tmpl};
state->buffer = (PsycString) {buflen, buffer};
state->open = (PsycString) {openlen, open};
state->close = (PsycString) {closelen, close};
}
/**
* Sets a new output buffer in the PSYC text state struct.
*/
static inline
void psyc_text_buffer_set (PsycTextState *state,
char *buffer, size_t length)
{
state->buffer = (PsycString){length, buffer};
state->written = 0;
}
static inline
size_t psyc_text_bytes_written (PsycTextState *state)
{
return state->written;
}
/**
* Fills out text templates by asking a callback for content.
*
* Copies the contents of the template into the buffer while looking for the
* opening and closing brace strings and calling the callback for each enclosed
* string between these braces. Should the callback return
* PSYC_TEXT_VALUE_NOT_FOUND, the original template text is copied as is.
*
* Before calling this function psyc_text_state_init should be called to initialize
* the state struct. By default PSYC's "[" and "]" are used but you can provide
* any other brace strings such as "${" and "}" or "<!--" and "-->" if you use
* the psyc_text_state_init_custom variant.
*
* @see http://about.psyc.eu/psyctext
**/
PsycTextRC psyc_text (PsycTextState *state, PsycTextCB getValue, void *extra);
/** @} */ // end of text group
#define PSYC_TEXT_H
#endif