Viewing file:  AST_lower_expr.cpp (3.61 KB) -rw-rw-r--
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/*
* phc -- the open source PHP compiler
* See doc/license/README.license for licensing information
*
* Generic superclass for transformations that replace expressions
* by multiple statements
*/
#include "AST_lower_expr.h"
#include "process_ir/fresh.h"
#include "process_ir/General.h"
using namespace AST;
void Lower_expr::children_php_script(PHP_script* in)
{
pieces = new Statement_list;
Transform::children_php_script(in);
}
/*
* For each statement that contains an expression, we push back the
* pieces created for each part of the expression.
*/
void Lower_expr::post_eval_expr (Eval_expr* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::post_global (Global* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::post_return (Return* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::post_continue (Continue* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::post_break (Break* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::post_throw (Throw* in, Statement_list* out)
{
push_back_pieces(in, out);
}
/*
* For each control-flow statement that contains an expression, we
* push back the pieces created for each part of the expression, but
* before the statement, since it can contain sub-statements.
*/
/* Avoid putting the pieces from the expression into the body */
void Lower_expr::children_if (If* in)
{
in->expr = transform_expr(in->expr);
backup_pieces();
in->iftrue = transform_statement_list(in->iftrue);
in->iffalse = transform_statement_list(in->iffalse);
restore_pieces();
}
void Lower_expr::post_if (If* in, Statement_list* out)
{
push_back_pieces(in, out);
}
void Lower_expr::children_while (While* in)
{
in->expr = transform_expr(in->expr);
backup_pieces();
in->statements = transform_statement_list(in->statements);
restore_pieces();
}
void Lower_expr::post_while (While* in, Statement_list* out)
{
push_back_pieces(in, out);
}
// No need to mess with the key and val, as they are written to,
// not read from. Early_lower_control_flow deals with them.
void Lower_expr::children_foreach (Foreach* in)
{
in->expr = transform_expr(in->expr);
backup_pieces();
in->statements = transform_statement_list(in->statements);
restore_pieces();
}
void Lower_expr::post_foreach (Foreach* in, Statement_list* out)
{
push_back_pieces(in, out);
}
/*
* Pushing back, storing and restoring pieces
*/
void Lower_expr::push_back_pieces(Statement* in, Statement_list* out)
{
out->push_back_all(pieces);
out->push_back(in);
// Move comment to the first piece (if any)
if(!pieces->empty())
{
pieces->front()->attrs->set("phc.comments", in->get_comments());
in->attrs->set("phc.comments", new String_list);
}
pieces->clear();
}
void Lower_expr::backup_pieces()
{
pieces_backup.push(pieces);
pieces = new Statement_list;
}
void Lower_expr::restore_pieces()
{
pieces = pieces_backup.top();
pieces_backup.pop();
}
/*
* A common pattern is captured by "eval", which takes an argument
* an expression e, generates a new temporary T, and pushes back the
* statement
*
* T = e;
*
* the value returned is the expression "T".
*
* If the node is marked "phc.lower_expr.no_temp", eval simply
* returns in.
*/
Expr* Lower_expr::eval(Expr* in)
{
if(in->attrs->is_true("phc.ast_lower_expr.no_temp"))
{
return in;
}
else
{
Variable* temp = fresh_var("TLE");
eval(in, temp);
return temp;
}
}
// Variation on eval that takes in the name of the temp
void Lower_expr::eval(Expr* in, Variable* temp)
{
pieces->push_back(new Eval_expr(new Assignment(temp->clone (), false, in->clone ())));
}
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