200 lines
7.1 KiB
C
200 lines
7.1 KiB
C
/* Definitions for expressions stored in reversed prefix form, for GDB.
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Copyright (C) 1986, 1989 Free Software Foundation, Inc.
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This file is part of GDB.
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GDB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 1, or (at your option)
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any later version.
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GDB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GDB; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* Definitions for saved C expressions. */
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/* An expression is represented as a vector of union exp_element's.
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Each exp_element is an opcode, except that some opcodes cause
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the following exp_element to be treated as a long or double constant
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or as a variable. The opcodes are obeyed, using a stack for temporaries.
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The value is left on the temporary stack at the end. */
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/* When it is necessary to include a string,
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it can occupy as many exp_elements as it needs.
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We find the length of the string using strlen,
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divide to find out how many exp_elements are used up,
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and skip that many. Strings, like numbers, are indicated
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by the preceding opcode. */
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enum exp_opcode
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{
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/* BINOP_... operate on two values computed by following subexpressions,
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replacing them by one result value. They take no immediate arguments. */
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BINOP_ADD, /* + */
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BINOP_SUB, /* - */
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BINOP_MUL, /* * */
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BINOP_DIV, /* / */
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BINOP_REM, /* % */
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BINOP_LSH, /* << */
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BINOP_RSH, /* >> */
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BINOP_AND, /* && */
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BINOP_OR, /* || */
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BINOP_LOGAND, /* & */
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BINOP_LOGIOR, /* | */
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BINOP_LOGXOR, /* ^ */
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BINOP_EQUAL, /* == */
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BINOP_NOTEQUAL, /* != */
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BINOP_LESS, /* < */
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BINOP_GTR, /* > */
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BINOP_LEQ, /* <= */
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BINOP_GEQ, /* >= */
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BINOP_REPEAT, /* @ */
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BINOP_ASSIGN, /* = */
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BINOP_COMMA, /* , */
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BINOP_SUBSCRIPT, /* x[y] */
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BINOP_EXP, /* Exponentiation */
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/* C++. */
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BINOP_MIN, /* <? */
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BINOP_MAX, /* >? */
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BINOP_SCOPE, /* :: */
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/* STRUCTOP_MEMBER is used for pointer-to-member constructs.
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X . * Y translates into X STRUCTOP_MEMBER Y. */
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STRUCTOP_MEMBER,
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/* STRUCTOP_MPTR is used for pointer-to-member constructs
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when X is a pointer instead of an aggregate. */
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STRUCTOP_MPTR,
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/* end of C++. */
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BINOP_END,
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BINOP_ASSIGN_MODIFY, /* +=, -=, *=, and so on.
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The following exp_element is another opcode,
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a BINOP_, saying how to modify.
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Then comes another BINOP_ASSIGN_MODIFY,
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making three exp_elements in total. */
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/* Operates on three values computed by following subexpressions. */
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TERNOP_COND, /* ?: */
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/* The OP_... series take immediate following arguments.
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After the arguments come another OP_... (the same one)
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so that the grouping can be recognized from the end. */
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/* OP_LONG is followed by a type pointer in the next exp_element
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and the long constant value in the following exp_element.
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Then comes another OP_LONG.
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Thus, the operation occupies four exp_elements. */
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OP_LONG,
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/* OP_DOUBLE is similar but takes a double constant instead of a long one. */
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OP_DOUBLE,
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/* OP_VAR_VALUE takes one struct symbol * in the following exp_element,
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followed by another OP_VAR_VALUE, making three exp_elements. */
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OP_VAR_VALUE,
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/* OP_LAST is followed by an integer in the next exp_element.
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The integer is zero for the last value printed,
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or it is the absolute number of a history element.
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With another OP_LAST at the end, this makes three exp_elements. */
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OP_LAST,
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/* OP_REGISTER is followed by an integer in the next exp_element.
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This is the number of a register to fetch (as an int).
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With another OP_REGISTER at the end, this makes three exp_elements. */
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OP_REGISTER,
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/* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
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With another OP_INTERNALVAR at the end, this makes three exp_elements. */
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OP_INTERNALVAR,
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/* OP_FUNCALL is followed by an integer in the next exp_element.
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The integer is the number of args to the function call.
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That many plus one values from following subexpressions
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are used, the first one being the function.
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The integer is followed by a repeat of OP_FUNCALL,
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making three exp_elements. */
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OP_FUNCALL,
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/* OP_STRING represents a string constant.
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Its format is the same as that of a STRUCTOP, but the string
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data is just made into a string constant when the operation
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is executed. */
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OP_STRING,
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/* UNOP_CAST is followed by a type pointer in the next exp_element.
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With another UNOP_CAST at the end, this makes three exp_elements.
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It casts the value of the following subexpression. */
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UNOP_CAST,
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/* UNOP_MEMVAL is followed by a type pointer in the next exp_element
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With another UNOP_MEMVAL at the end, this makes three exp_elements.
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It casts the contents of the word addressed by the value of the
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following subexpression. */
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UNOP_MEMVAL,
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/* UNOP_... operate on one value from a following subexpression
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and replace it with a result. They take no immediate arguments. */
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UNOP_NEG, /* Unary - */
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UNOP_ZEROP, /* Unary ! */
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UNOP_LOGNOT, /* Unary ~ */
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UNOP_IND, /* Unary * */
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UNOP_ADDR, /* Unary & */
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UNOP_PREINCREMENT, /* ++ before an expression */
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UNOP_POSTINCREMENT, /* ++ after an expression */
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UNOP_PREDECREMENT, /* -- before an expression */
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UNOP_POSTDECREMENT, /* -- after an expression */
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UNOP_SIZEOF, /* Unary sizeof (followed by expression) */
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/* STRUCTOP_... operate on a value from a following subexpression
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by extracting a structure component specified by a string
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that appears in the following exp_elements (as many as needed).
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STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
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They differ only in the error message given in case the value is
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not suitable or the structure component specified is not found.
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The length of the string follows in the next exp_element,
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(after the string), followed by another STRUCTOP_... code. */
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STRUCTOP_STRUCT,
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STRUCTOP_PTR,
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/* C++ */
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/* OP_THIS is just a placeholder for the class instance variable.
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It just comes in a tight (OP_THIS, OP_THIS) pair. */
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OP_THIS,
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/* OP_SCOPE surrounds a type name and a field name. The type
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name is encoded as one element, but the field name stays as
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a string, which, of course, is variable length. */
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OP_SCOPE,
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};
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union exp_element
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{
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enum exp_opcode opcode;
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struct symbol *symbol;
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LONGEST longconst;
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double doubleconst;
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char string;
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struct type *type;
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struct internalvar *internalvar;
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};
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struct expression
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{
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int nelts;
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union exp_element elts[1];
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};
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/* From expread.y. */
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struct expression *parse_c_expression ();
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struct expression *parse_c_1 ();
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/* The innermost context required by the stack and register variables
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we've encountered so far. To use this, set it to NULL, then call
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parse_c_<whatever>, then look at it. */
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extern struct block *innermost_block;
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/* From expprint.c. */
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void print_expression ();
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