- Move Heap and Frame/Scope to their own headers.
- Move some functions to more appropriate headers (e.g. CopyValue -> value.h).
- Define a separate Bazel rule for each header/cpp pair.
- Modify PrintValue to not print the frames of a ContinuationValue. This was necessary to break a dependency cycle between PrintValue, PrintFrame, and Action::Print.
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
Note this makes some structural choices that I'm not sure how popular they'll be... Most notably, I could remove `DeclarationKind` because I'm using `std::visit` and `Declaration::Visitor` in reality. I could go to `switch(tag())` instead, but I'm wondering if this approach will be well received for the separation of ownership. Alternatively, I could move `Declaration` around so that it actually implements the things like `TopLevel` -- I did feel weird with the old structure of typecheck.cpp implementing members of declaration.h, though.
We will eventually need the ability to materialize temporaries eventually, but we don't really seem to need it yet, and when we do, I think we should do it in a way that gives uniform treatment to temporaries and local variables.
Also:
- Switch data members, and associated parameters and return types to be values/references rather than pointers, where applicable.
- Move Expression's TagVisitor to anonymous namespace, to avoid name collision.
- Switch to trailing return syntax (per style guide).
Pretty much any names will be awkward, since these types represent cases where an `Expression` is not an expression, and a `Value` is not a value, but we can at least be more explicit about the fact that they represent bindings rather than variable usages.
- `Kind` enumerator names always match the corresponding factory function, accessor, and type names (if any).
- All abbreviations in those names are expanded.
- Those names always have a suffix to disambiguate expressions from values.
`VarTV` is excluded from these changes because there's a pending PR to remove it.
* moved most of logic from HandleValue into the Step functions
* removed the HandleValue function
* added some comments
* responses to Geoffrey
* move increment of act->pos out of the step logic for value actions
* changed act->pos to start at 0 and not have any gaps
* Update executable_semantics/interpreter/action.h
Co-authored-by: Geoff Romer <gromer@google.com>
* update comment based on Geoffrey's suggestion
Co-authored-by: Geoff Romer <gromer@google.com>
The presence or absence of whitespace is used to determine which
operator is in use, following the rules described in #520.
Support for prefix * dereference operator follows #523.
Co-authored-by: Geoff Romer <gromer@google.com>
* changed union of Statement to be private
* changed the union in Expression to be private
* changed union in Value to be private
* changed AST constructors to be static methods
* updates to syntax unit tests
Additional miscellaneous cleanup:
- Use the term "deallocate" instead of "kill" in function names, for symmetry with "allocate".
- Drop an unnecessary memory allocation in `AllocateValue`.
- Implement `PrintHeap` in terms of `PrintAddress`, so that dead values are flagged with `!!`.
* improved checking for liveness when reading and writing memory
* moving some functions to be methods of State
* finished moving functions into State
* Update executable_semantics/interpreter/interpreter.h
Co-authored-by: Geoff Romer <gromer@google.com>
* moved some comments, other minor edits
Co-authored-by: Geoff Romer <gromer@google.com>
* AST and syntax for delimited control
* stashing for later
* a little more progress
* progress on delimited continuations
* delimit, suspend, and resume implemented (draft)
* example that generates the natural numbers
* fixes
* tinkering
* changed demo to experimental
* comments and name changes
* describe delimited continuations in the README
* renamed Snapshot to Continuation, edits to comments
* Update executable_semantics/ast/statement.h
improve comment for MakeDelimitStmt
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* Update executable_semantics/interpreter/interpreter.cpp
remove snake_case
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* edits to comments, change name of variable
* updates to handle review edits
* trailing whitespace
* fixes to delimited continuations, added more tests, also fixed assignment to do a copy
* improvements from Geoffrey
* new test from Geoffrey, fix for empty blocks
* more suggestions from Geoffrey
* more tests for delimited continuations, renaming some of them
* renamed test files
* improve a comment
* sketch of creating continuation
* initial implementation of shift/reset style continuations
* more documentation
* fix some camel case
* implemented deep copy of continuations, added a test case for it
* fixed a bug and got the recursive test case working
* removed __delimit, polished up __continuation
* back to shallow copy for continuations
* suggestions from Geoffrey
* removed structured binding (for now)
* Update executable_semantics/ast/expression.cpp
Co-authored-by: Geoff Romer <gromer@google.com>
* responses to Geoffrey
Co-authored-by: Dave Abrahams <dabrahams@google.com>
Co-authored-by: Geoff Romer <gromer@google.com>
Making Values const allows us to separate the actual mutations (search for "*&" in this change) from places where the Value is effectively passed by-value.
* separate the alive flag from the Value class
* restored KillValue, added KillAddress
* added comments
* Update executable_semantics/interpreter/interpreter.cpp
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* Update executable_semantics/interpreter/interpreter.cpp
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* Update executable_semantics/interpreter/interpreter.cpp
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* finish edits from Dave
Co-authored-by: Dave Abrahams <dabrahams@google.com>
* global variables
* implemented type checking of global variable, added test case
* added a comment
* improvements based on Dave's suggestions
* improvements based on Jon's suggestions
* added test cases about global variable ordering
* add command-line flag to enable/disable tracing output
* adding missing exit for pattern variable in wrong context and a test case for it (#324)
* Update executable_semantics/interpreter/interpreter.cpp
comment on separate line as code
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
* fix interpreter's handling of optional else of if statement (#323)
* Update pattern_variable_fail.golden due to error (#334)
* Use llvm's CommandLine for parsing (#332)
* GitHub testing action (#331)
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
* add copyright
* Create a Dictionary abstraction over the raw Cons list. (#327)
* Create a Dictionary abstraction over the raw Cons list.
* renamed Cons and some methods of Dictionary, various other cleanup
* Update executable_semantics/tracing_flag.cpp
added namespace comment
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
* added a comment to cpp file
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
Co-authored-by: Dave Abrahams <dabrahams@google.com>
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
* improve abstraction for AssocList, fix bug in optional else
* add flag for tracing output, clean up code for output
* turned off tracing by default, updated goldens, removed two examples that use pointers, shouldn't have been there yet
This change creates an unpleasant amount of boilerplate where `Declaration` is declared, in exchange for being able to—very pleasantly—treat it as a simple value that composes with other values everywhere it is used. Applying this technique broadly will pay off in code comprehensibility; once it has been done for all things being new'd, pointers disappear and references are only needed as an idiomatic approximation of inout. The unpleasant code grows only when new polymorphic operations are added, and then only a bit, and is an idiom whose details can readily be ignored once in place. The pleasant code pervades the codebase.
Too bad we don't have existential types in C++ ;-)
* Add assertion to detect UB in interpreter.cpp
This change, applied to 6e5070d ("Adapting jsiek's executable semantics tooling
for commit. (#237)"), causes the if2.6c test to segfault. Becase the assertion
fires only when `stmt == nullptr` and no code has permission to change `stmt`
(it is `const`) before it is dereferenced in the `switch`, and nothiing in
`PrintStatement` is supposed to exit the program, the assertion is a valid
change that detects a bug.
The crash was originally manifest in 29a5994 ("Executable Semantics: 1st-class
stacks (#296)").
* Temporarily disable the if2 test pending #311
See https://github.com/carbon-language/carbon-lang/issues/311
* [executable semantics] Record exit code on expected error.
This will prevent a final segfault from sneaking by, detected as a passing test.
A more principled follow-up commit would bottleneck detected error exit
reporting and have it write something to std::cerr that can be recognized.
* [executable semantics] class-ify Declaration
NFC (no functional change).
Proof of concept that we can simplify code by replacing unions with safer, more
regular types. Hand-rolled existentials (type-erasing CoW wrappers) are a follow-on
step that will further simplify usage.
Began adding `const` where possible, and replacing `std::string*` with
`std::string`. Most `const`s can disappear as we replace reference semantics
with value semantics, but in the meantime it's an important step in the right
direction.
Replaces low-level uses of `Cons` with a first-class `Stack` data structure. Also removes an unused algorithm.
Co-authored-by: Jeremy Siek <jsiek@indiana.edu>
Possible next step: use `std::stack` instead.
Jon Meow
Geoff RomerandJon Meow
Jeremy G. SiekandGeoff Romer
Richard SmithandGeoff Romer
