The expression ‘await e’ always suspends the enclosing function. If e does not
evaluate to a an object o of type Future, a new Future is created using Future.value(o).
A small change in the backend allows a return instruction to be followed by
other instructions. In async functions, a return can suspend the function and the
continuation point is in the same code block after the return.
Other small changes:
- More user-friendly error message if async/await is not enabled.
- Programs no longer need to import dart:async when using async/await.
R=fschneider@google.com
Review URL: https://codereview.chromium.org//634603002
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@41105 260f80e4-7a28-3924-810f-c04153c831b5
This CL adds basic infrastructure needed for awaitable expressions. Implementation of continuations is not part of this CL.
Expressions containing ``await'' are transformed into a series of operations on intermediates, effectively getting rid
of the temporary expression stack. Currently only expressions evaluating to an actual value (read: non-future) are supported.
Also, not all kinds of statements support awaitable expressions yet.
Missing:
* Capturing all (needed) variables
* Continuations (connecting a preamble with await statements; re-adding the closure to the run queue)
BUG=
R=hausner@google.com
Review URL: https://codereview.chromium.org//447003003
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@39345 260f80e4-7a28-3924-810f-c04153c831b5
The print-ast output is useful for debugging front end issues. It is a mix
of fully-parenthesized prefix notation (i.e., Lisp S-expressions) with some
infix.
It is not valid S-expressions for various other reasons. Most obviously, it
uses ' (single quote) instead of " (double quote) to delimit strings.
This change makes the print-ast output a valid Scheme S-expression. It can
be pretty printed by copying it, quoting it (by preceding it with a single
quote), and evaluating it at the REPL of a Scheme implementation.
Also, the AST node pretty names are changed to predictably match the class
name. It doesn't seem helpful to have them be arbitrary.
BUG=
R=regis@google.com
Review URL: https://codereview.chromium.org//23923005
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27282 260f80e4-7a28-3924-810f-c04153c831b5
The Name function is used for pretty printing except that for a few
node types we rely on a specific name for implementation correctness.
Overriding the pretty printing function to get out a type name, or a
variable name, or an operator symbol name, is risky.
1. Code that relies on the semantics of the name will break if the
pretty name is changed.
2. Pretty printing is less useful. For instance, LoadLocalNode just
prints the variable name (twice, once as the AST constructor and
once in quotes as the variable name). This is confusing if the
variable happens to have the same name as one of the other pretty
names, e.g., args or seq.
Now, there is a virtual function to get the pretty name but classes do
not change it to communicate other information (type names, variable
names, operator names).
BUG=
R=regis@google.com, srdjan@google.com
Review URL: https://codereview.chromium.org//23960003
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27244 260f80e4-7a28-3924-810f-c04153c831b5
This CL affects a subset of expressions that use temporary locals: constructor
calls, array literals and and instance getter postfix-ops.
For expressions that are de-sugared in the parser I added LetNode.
It creates a scoped temporary local bound to an initializing expression.
For expressions where we need a temporary local at graph-building time,
I added a helper class TempLocalScope to easily create a single temporary
local in the graph builder since this is a frequently recurring pattern.
This simplifies code in the parser and the graph builder and also fixes a
bug with indexed-super invocation and NoSuchMethod.
BUG=dart:8918
R=kmillikin@google.com
Review URL: https://codereview.chromium.org//14942010
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@23401 260f80e4-7a28-3924-810f-c04153c831b5
This change introduces variable descriptors that describe the name, stack slot index, and source code stretch in which a variable is valid.
Activation frames in the stack trace now can enumerate the variables that are active in that frame.
Next step: fetch the value of variables from the stack.
Review URL: http://codereview.chromium.org//8992020
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@2671 260f80e4-7a28-3924-810f-c04153c831b5
hausner@google.com