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* jv-exp.y (ArrayAccess): Implement Name [ Expression ]; check the 

code to see why this is not trivial.
(copy_exp, insert_exp): New functions.
This commit is contained in:
Jim Blandy 1997-11-04 21:54:13 +00:00
parent 3b5bd034f5
commit 028da17987
1 changed files with 71 additions and 4 deletions
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75
gdb/jv-exp.y
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@ -18,14 +18,14 @@ You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Parse a C expression from text in a string,
/* Parse a Java expression from text in a string,
and return the result as a struct expression pointer.
That structure contains arithmetic operations in reverse polish,
with constants represented by operations that are followed by special data.
See expression.h for the details of the format.
What is important here is that it can be built up sequentially
during the process of parsing; the lower levels of the tree always
come first in the result.
come first in the result. Well, almost always; see ArrayAccess.
Note that malloc's and realloc's in this file are transformed to
xmalloc and xrealloc respectively by the same sed command in the
@ -112,6 +112,9 @@ static struct type * java_type_from_name PARAMS ((struct stoken));
static void push_expression_name PARAMS ((struct stoken));
static void push_fieldnames PARAMS ((struct stoken));
static struct expression *copy_exp PARAMS ((struct expression *, int));
static void insert_exp PARAMS ((int, struct expression *));
%}
/* Although the yacc "value" of an expression is not used,
@ -442,8 +445,22 @@ MethodInvocation:
ArrayAccess:
Name '[' Expression ']'
/* FIXME - This is nasty - need to shuffle expr stack. */
{ error ("`Name[Expr]' not implemented yet - try `(Name)[Expr]'"); }
{
/* Emit code for the Name now, then exchange it in the
expout array with the Expression's code. We could
introduce a OP_SWAP code or a reversed version of
BINOP_SUBSCRIPT, but that makes the rest of GDB pay
for our parsing kludges. */
struct expression *name_expr;
push_expression_name ($1);
name_expr = copy_exp (expout, expout_ptr);
expout_ptr -= name_expr->nelts;
insert_exp (expout_ptr-length_of_subexp (expout, expout_ptr),
name_expr);
free (name_expr);
write_exp_elt_opcode (BINOP_SUBSCRIPT);
}
| VARIABLE '[' Expression ']'
{ write_exp_elt_opcode (BINOP_SUBSCRIPT); }
| PrimaryNoNewArray '[' Expression ']'
@ -1378,3 +1395,53 @@ push_expression_name (name)
}
}
/* The following two routines, copy_exp and insert_exp, aren't specific to
Java, so they could go in parse.c, but their only purpose is to support
the parsing kludges we use in this file, so maybe it's best to isolate
them here. */
/* Copy the expression whose last element is at index ENDPOS - 1 in EXPR
into a freshly malloc'ed struct expression. Its language_defn is set
to null. */
static struct expression *
copy_exp (struct expression *expr, int endpos)
{
int len = length_of_subexp (expr, endpos);
struct expression *new
= (struct expression *) malloc (sizeof (*new) + EXP_ELEM_TO_BYTES (len));
new->nelts = len;
memcpy (new->elts, expr->elts + endpos - len, EXP_ELEM_TO_BYTES (len));
new->language_defn = 0;
return new;
}
/* Insert the expression NEW into the current expression (expout) at POS. */
static void
insert_exp (int pos,
struct expression *new)
{
int newlen = new->nelts;
/* Grow expout if necessary. In this function's only use at present,
this should never be necessary. */
if (expout_ptr + newlen > expout_size)
{
expout_size = max (expout_size * 2, expout_ptr + newlen + 10);
expout = (struct expression *)
realloc ((char *) expout, (sizeof (struct expression)
+ EXP_ELEM_TO_BYTES (expout_size)));
}
{
int i;
for (i = expout_ptr - 1; i >= pos; i--)
expout->elts[i + newlen] = expout->elts[i];
}
memcpy (expout->elts + pos, new->elts, EXP_ELEM_TO_BYTES (newlen));
expout_ptr += newlen;
}