92 lines
1.9 KiB
C
92 lines
1.9 KiB
C
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/*
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* $Id$
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*
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* This is really two parts -- the lexer and the parser. Converting
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* a parse tree back to a format that works with the database backend
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* is left to the db backend.
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*
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* Oh, and this is called "smart-parser" because it parses terms for
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* specifying smart playlists, not because it is particularly smart. :)
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "err.h"
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typedef struct tag_parsetree {
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char *term;
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int token;
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int next_token;
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} PARSESTRUCT, *PARSETREE;
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#define SP_TOK_EOF 0
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/**
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* set up the initial parse tree
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*
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* @returns opaque parsetree struct
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*/
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PARSETREE sp_init(void) {
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PARSETREE ptree;
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ptree = (PARSETREE)malloc(sizeof(PARSESTRUCT));
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if(!ptree)
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DPRINTF(E_FATAL,L_PARSE,"Alloc error\n");
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memset(ptree,0,sizeof(PARSESTRUCT));
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return ptree;
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}
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/**
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* parse a term or phrase into a tree.
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*
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* @param tree parsetree previously created with sp_init
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* @param term term or phrase to parse
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* @returns 1 if successful, 0 if not
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*/
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int sp_parse(PARSETREE tree, char *term) {
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tree->term = strdup(term); /* will be destroyed by parsing */
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while(sp_scan(tree)) {
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if(tree->token == SP_TOK_EOF)
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return 1; /* valid tree! */
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/* otherwise, keep scanning until done or error */
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}
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}
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/**
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* dispose of an initialized tree
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*
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* @param tree tree to dispose
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* @returns 1
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*/
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int sp_dispose(PARSETREE tree) {
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if(tree->term)
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free(tree->term);
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free(tree);
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return 1;
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}
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/**
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* if there was an error in a previous action (parsing?)
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* then return that error to the client. This does not
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* clear the error condition -- multiple calls to sp_geterror
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* will return the same value.
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*
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* memory handling is done on the smart-parser side.
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*
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* @param tree tree that generated the last error
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* @returns text of the last error
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*/
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char *sp_geterror(PARSETREE tree) {
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return "blah";
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}
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