Allow user defined functions to be parsed.

[ginac.git] / ginac / parser / parse_context.h

diff --git a/ginac/parser/parse_context.h b/ginac/parser/parse_context.h
index c7360ddd86c74c1e898efe69667941c67a07be8d..81b2cd15a9ada239ae9c2e55efaa32fce66a455f 100644 (file)
--- a/ginac/parser/parse_context.h
+++ b/ginac/parser/parse_context.h
@@ -3,7 +3,7 @@
  *  Interface to parser context. */
 
 /*
- *  GiNaC Copyright (C) 1999-2009 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -41,12 +41,12 @@ namespace GiNaC {
 typedef std::map<std::string, ex> symtab;
 
 /**
- * Find the symbol with the @a name in the symbol table @a syms.
+ * Find the symbol (or abbreviation) with the @a name in the symbol table @a syms.
  *
  * If symbol is missing and @a strict = false, insert it, otherwise
  * throw an exception.
  */
-extern symbol
+extern ex 
 find_or_insert_symbol(const std::string& name, symtab& syms,
                      const bool strict);
 
@@ -72,18 +72,30 @@ typedef ex (*reader_func)(const exvector& args);
  * foo(x+y, z^2, t)), it looks up such a table to find out which
  * function (or class) corresponds to the given name and has the given
  * number of the arguments.
+ *
+ * N.B.
+ *
+ * 1. The function don't have to return a (GiNaC) function or class, it
+ *    can return any expression.
+ * 2. Overloaded functions/ctors are paritally supported, i.e. there might
+ *    be several functions with the same name, but they should take different
+ *    number of arguments.
+ * 3. User can extend the parser via custom prototype tables. It's possible
+ *    to read user defined classes, create abbreviations, etc.
+ *
+ * NOTE: due to a hack that allows user defined functions to be parsed, the map
+ *       value of type reader_func is internally treated as an unsigned and not as a
+ *       function pointer!! The unsigned has to correspond to the serial number of
+ *       the defined GiNaC function.
  */
-typedef std::map<prototype, unsigned> prototype_table;
+typedef std::map<prototype, reader_func> prototype_table;
 
 /**
- * Creates a default prototype table containing all defined GiNaC functions.
+ * Default prototype table.
  *
- * The data referenced by the return value is only created once when this
- * function is called for the first time. This might cause problems in very
- * rare stituations (i.e. if functions are added after this first call). In
- * that case, a new initialization can be forced with an "true" argument.
+ * It supports most of builtin GiNaC functions.
  */
-extern const prototype_table& get_default_reader(bool force_init = false);
+extern const prototype_table& get_default_reader();
 
 } // namespace GiNaC