[BUGFIX] Fix crash in parser.

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

diff --git a/ginac/parser/parse_context.h b/ginac/parser/parse_context.h
index b227c6654fb40d4e917e39e0067b859f5865ef60..015ca13517dbce52410fa67a8317030e5a3ce30f 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) 1999-2010 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2024 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);
 
@@ -63,7 +63,21 @@ typedef std::pair<std::string, std::size_t> prototype;
  * The parser uses (an associative array of) such functions to construct
  * (GiNaC) classes and functions from a sequence of characters.
  */
-typedef ex (*reader_func)(const exvector& args);
+class reader_func {
+       enum { FUNCTION_PTR, GINAC_FUNCTION };
+public:
+       reader_func(ex (*func_)(const exvector& args))
+               : type(FUNCTION_PTR), serial(0), func(func_) {}
+       reader_func(unsigned serial_)
+               : type(GINAC_FUNCTION), serial(serial_), func(nullptr) {}
+       ex operator()(const exvector& args) const;
+private:
+       unsigned type;
+       unsigned serial;
+       ex (*func)(const exvector& args);
+};
+
+
 
 /**
  * Prototype table.
@@ -72,18 +86,49 @@ 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;
+class PrototypeLess
+{
+public:
+       bool operator()(const prototype& p1, const prototype& p2) const
+       {
+               int s = p1.first.compare(p2.first);
+               if (s == 0) {
+                       if ((p1.second == 0) || (p2.second == 0)) return false;
+                       return p1.second < p2.second;
+               }
+               return s < 0;
+       }
+};
+typedef std::map<prototype, reader_func, PrototypeLess> prototype_table;
 
 /**
- * Creates a default prototype table containing all defined GiNaC functions.
+ * Default prototype table.
+ *
+ * It supports all defined GiNaC functions and "pow", "sqrt", and "power".
+ */
+extern const prototype_table& get_default_reader();
+/**
+ * Builtin 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 only the builtin GiNaC functions and "pow", "sqrt", and "power".
  */
-extern const prototype_table& get_default_reader(bool force_init = false);
+extern const prototype_table& get_builtin_reader();
 
 } // namespace GiNaC