- Give unary `-` and `not` the same precedence as in C++
- Add detail to parse error messages, and make the --trace flag also enable parser debug tracing
- Make any new shift-reduce conflicts into build errors
- Use `%precedence` rather than `%nonassoc` where possible, in order to catch more grammar bugs at build time
* Move nontrivial logic out of `parser.ypp` into `FieldList`, rename it to `ParenContents`, make it a class, and add tests
* Use a `FieldInitializer` struct instead of `std::pair<std::string, Expression*>` to represent the fields of a tuple
* 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
We're now one step away from eliminating bare pointers in semantic actions.
There are plenty of other cleanups and modernizations that can be made in the
parser, but the elimination of bare pointers is the one that has the highest
impact for the codebase.
Slowly bringing this into line with Bison's C++ example parser
so we can use strong semantic values for symbols rather than
leaking pointers. First step is to thread a `ParseAndLexContext`
object through the whole syntactic analysis state, like the
example has. In the example, it's called `driver`.
Co-authored-by: Geoff Romer <gromer@google.com>
Distinguishes parts that come from the parser and lexer. It used to be that all
the files were called "syntax*", but lexing and parsing are distinct phases that
are easier to keep track of when distinguished. syntax.yy.cpp being the source
file generated by flex, containing the lexer was particularly confusing, because
the yy tends to indicate it is a yacc/Bison product, and the ".tab." substring,
indicating "tables" is not really useful to the developer.
These names also match up with what Bison's C++ example uses, which will make
the transition easier.
* 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>
* Make `field_list` always a list.
* Create separate `paren_expression` and `tuple` nonterminals
* Rename expression_or_field_list.* to field_list.*
Co-authored-by: Jeremy G. Siek <jsiek@indiana.edu>
* 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.
* Make parentheses optional for alternatives with no arguments.
* Use `,` instead of `;` as separator for alternatives, and make the trailing separator optional.
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.
This makes executable semantics build and pass tests for me without
installing either Bison or Flex. We just use the primitive toolchain
with the existing genrule as the packaged rules don't quite fit how
we're building and organizing the code.
Currently, this points at forks of the upstream rule repositories while
PRs I have sent there are going through, but this should be functional
for now and there doesn't seem to be any reason to wait for those PRs to
go through.
Notes versus what jsiek wrote:
- This adopts Bazel for building.
- System-local versions of bison/flex are used. I found https://github.com/jmillikin/rules_bison, but those print a lot of warnings (things like -Wsign-compare IIRC) which makes builds hard to read. Plus I think the underlying bison_cc_library rule didn't work, so this would really only get a hermetic bison/flex build (helpful, but didn't seem worth more time).
- I'm adding in a .bazeliskrc to push a somewhat more standard choice of bazel versions. I noticed I was getting unstable versions by default, possible Google-specific, but seemed good to include.
- The `-lpthread` kludge.
- Turn all of the examples into golden tests.
- Including adding a golden test rule.
- Fixed various style guide issues. For example:
- Fixing function names to be CamelCase instead of snake_case (https://google.github.io/styleguide/cppguide.html#Function_Names)
- Removed exception use (https://google.github.io/styleguide/cppguide.html#Exceptions)
- File name fixes (https://github.com/carbon-language/carbon-lang/blob/trunk/docs/project/cpp_style_guide.md#file-names)
- Dropped `using` of `std` names -- I believe this is preferred (maybe we should be explicit about this in the Carbon style guide)
- Switched `enum` uses to `enum class` for ease-of-identification.
- Spent some time breaking out files to hopefully be easier to read/edit pieces, and understand relations between structs.
- Added `code requires` to `syntax.ypp` to address include issues
Possibly other things -- but the fundamental structure is, I believe, unchanged. I put in the golden tests pretty early to ensure I wasn't mutating output/results.
Geoff Romer
Jeremy G. Siek
Jeremy G. SiekandJon Meow