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The CTPL engine is split, as most parsers, in two distinct parts: the lexer and the parser.
The lexer is the part that reads the actual input data, and tries to create a token tree (internal representation of the input) that the parser will use.
The parser reads a token tree and an environment, and outputs the computed template.
By exposing this separation of the tasks to the user, it is possible to parse a single template many times with a different environment without needing to re-lex it, which will save computation time and resources.
Example 1. Using the library to lex and parse a template
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#include <ctpl/ctpl.h> /** * procede_template: * @input: The input stream * @env: The environment against which parse the input. * @output: The output stream * @error: Return location for an error, or %NULL to ignore them. * * Parses and lexes a template. * * Returns: %TRUE on success, %FALSE on error. */ gboolean procede_template (CtplInputStream *input, CtplEnviron *env, CtplOutputStream *output, GError **error) { gboolean success = FALSE; CtplToken *tree; /* first, create a token tree from the input template */ tree = ctpl_lexer_lex (input, error); if (tree != NULL) { /* then, parse this tree against the environment */ success = ctpl_parser_parse (tree, env, output, error); /* and finally, free the built tree */ ctpl_lexer_free_tree (tree); } return success; } |