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Allow multiple context managers in one with statement, as proposed

Browse source 
in http://codereview.appspot.com/53094 and accepted by Guido.

The construct is transformed into multiple With AST nodes so that
there should be no problems with the semantics.
This commit is contained in:
Georg Brandl 2009-05-25 21:02:56 +00:00
parent 04516611e7
commit 944f684ce6
11 changed files with 216 additions and 71 deletions
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63
Python/ast.c
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@ -3009,27 +3009,18 @@ ast_for_try_stmt(struct compiling *c, const node *n)
return TryFinally(body, finally, LINENO(n), n->n_col_offset, c->c_arena);
}
static expr_ty
ast_for_with_var(struct compiling *c, const node *n)
{
REQ(n, with_var);
return ast_for_expr(c, CHILD(n, 1));
}
/* with_stmt: 'with' test [ with_var ] ':' suite */
/* with_item: test ['as' expr] */
static stmt_ty
ast_for_with_stmt(struct compiling *c, const node *n)
ast_for_with_item(struct compiling *c, const node *n, asdl_seq *content)
{
expr_ty context_expr, optional_vars = NULL;
int suite_index = 3; /* skip 'with', test, and ':' */
asdl_seq *suite_seq;
assert(TYPE(n) == with_stmt);
context_expr = ast_for_expr(c, CHILD(n, 1));
REQ(n, with_item);
context_expr = ast_for_expr(c, CHILD(n, 0));
if (!context_expr)
return NULL;
if (TYPE(CHILD(n, 2)) == with_var) {
optional_vars = ast_for_with_var(c, CHILD(n, 2));
if (NCH(n) == 3) {
optional_vars = ast_for_expr(c, CHILD(n, 2));
if (!optional_vars) {
return NULL;
@ -3037,17 +3028,47 @@ ast_for_with_stmt(struct compiling *c, const node *n)
if (!set_context(c, optional_vars, Store, n)) {
return NULL;
}
suite_index = 4;
}
suite_seq = ast_for_suite(c, CHILD(n, suite_index));
if (!suite_seq) {
return NULL;
}
return With(context_expr, optional_vars, suite_seq, LINENO(n),
return With(context_expr, optional_vars, content, LINENO(n),
n->n_col_offset, c->c_arena);
}
/* with_stmt: 'with' with_item (',' with_item)* ':' suite */
static stmt_ty
ast_for_with_stmt(struct compiling *c, const node *n)
{
int i;
stmt_ty ret;
asdl_seq *inner;
REQ(n, with_stmt);
/* process the with items inside-out */
i = NCH(n) - 1;
/* the suite of the innermost with item is the suite of the with stmt */
inner = ast_for_suite(c, CHILD(n, i));
if (!inner)
return NULL;
for (;;) {
i -= 2;
ret = ast_for_with_item(c, CHILD(n, i), inner);
if (!ret)
return NULL;
/* was this the last item? */
if (i == 1)
break;
/* if not, wrap the result so far in a new sequence */
inner = asdl_seq_new(1, c->c_arena);
if (!inner)
return NULL;
asdl_seq_SET(inner, 0, ret);
}
return ret;
}
static stmt_ty
ast_for_classdef(struct compiling *c, const node *n, asdl_seq *decorator_seq)
{