Restructure and streamline token expansion
The purpose of this commit is to streamline the token expansion code, by
removing aspects of the code that are no longer relevant, removing
pointless duplication, and eliminating the need to pass the same
arguments to `expand_syntax`.
The first big-picture change in this commit is that instead of a handful
of `expand_` functions, which take a TokensIterator and ExpandContext, a
smaller number of methods on the `TokensIterator` do the same job.
The second big-picture change in this commit is fully eliminating the
coloring traits, making coloring a responsibility of the base expansion
implementations. This also means that the coloring tracer is merged into
the expansion tracer, so you can follow a single expansion and see how
the expansion process produced colored tokens.
One side effect of this change is that the expander itself is marginally
more error-correcting. The error correction works by switching from
structured expansion to `BackoffColoringMode` when an unexpected token
is found, which guarantees that all spans of the source are colored, but
may not be the most optimal error recovery strategy.
That said, because `BackoffColoringMode` only extends as far as a
closing delimiter (`)`, `]`, `}`) or pipe (`|`), it does result in
fairly granular correction strategy.
The current code still produces an `Err` (plus a complete list of
colored shapes) from the parsing process if any errors are encountered,
but this could easily be addressed now that the underlying expansion is
error-correcting.
This commit also colors any spans that are syntax errors in red, and
causes the parser to include some additional information about what
tokens were expected at any given point where an error was encountered,
so that completions and hinting could be more robust in the future.
Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>
Co-authored-by: Andrés N. Robalino <andres@androbtech.com>
* Clippy fixes
* Finish converting to use clippy
* fix warnings in new master
* fix windows
* fix windows
Co-authored-by: Artem Vorotnikov <artem@vorotnikov.me>
This commit contains two improvements:
- Support for a Range syntax (and a corresponding Range value)
- Work towards a signature syntax
Implementing the Range syntax resulted in cleaning up how operators in
the core syntax works. There are now two kinds of infix operators
- tight operators (`.` and `..`)
- loose operators
Tight operators may not be interspersed (`$it.left..$it.right` is a
syntax error). Loose operators require whitespace on both sides of the
operator, and can be arbitrarily interspersed. Precedence is left to
right in the core syntax.
Note that delimited syntax (like `( ... )` or `[ ... ]`) is a single
token node in the core syntax. A single token node can be parsed from
beginning to end in a context-free manner.
The rule for `.` is `<token node>.<member>`. The rule for `..` is
`<token node>..<token node>`.
Loose operators all have the same syntactic rule: `<token
node><space><loose op><space><token node>`.
The second aspect of this pull request is the beginning of support for a
signature syntax. Before implementing signatures, a necessary
prerequisite is for the core syntax to support multi-line programs.
That work establishes a few things:
- `;` and newlines are handled in the core grammar, and both count as
"separators"
- line comments begin with `#` and continue until the end of the line
In this commit, multi-token productions in the core grammar can use
separators interchangably with spaces. However, I think we will
ultimately want a different rule preventing separators from occurring
before an infix operator, so that the end of a line is always
unambiguous. This would avoid gratuitous differences between modules and
repl usage.
We already effectively have this rule, because otherwise `x<newline> |
y` would be a single pipeline, but of course that wouldn't work.
This commit extracts five new crates:
- nu-source, which contains the core source-code handling logic in Nu,
including Text, Span, and also the pretty.rs-based debug logic
- nu-parser, which is the parser and expander logic
- nu-protocol, which is the bulk of the types and basic conveniences
used by plugins
- nu-errors, which contains ShellError, ParseError and error handling
conveniences
- nu-textview, which is the textview plugin extracted into a crate
One of the major consequences of this refactor is that it's no longer
possible to `impl X for Spanned<Y>` outside of the `nu-source` crate, so
a lot of types became more concrete (Value became a concrete type
instead of Spanned<Value>, for example).
This also turned a number of inherent methods in the main nu crate into
plain functions (impl Value {} became a bunch of functions in the
`value` namespace in `crate::data::value`).
This commit extracts Tag, Span, Text, as well as source-related debug
facilities into a new crate called nu_source.
This change is much bigger than one might have expected because the
previous code relied heavily on implementing inherent methods on
`Tagged<T>` and `Spanned<T>`, which is no longer possible.
As a result, this change creates more concrete types instead of using
`Tagged<T>`. One notable example: Tagged<Value> became Value, and Value
became UntaggedValue.
This change clarifies the intent of the code in many places, but it does
make it a big change.
The original purpose of this PR was to modernize the external parser to
use the new Shape system.
This commit does include some of that change, but a more important
aspect of this change is an improvement to the expansion trace.
Previous commit 6a7c00ea adding trace infrastructure to the syntax coloring
feature. This commit adds tracing to the expander.
The bulk of that work, in addition to the tree builder logic, was an
overhaul of the formatter traits to make them more general purpose, and
more structured.
Some highlights:
- `ToDebug` was split into two traits (`ToDebug` and `DebugFormat`)
because implementations needed to become objects, but a convenience
method on `ToDebug` didn't qualify
- `DebugFormat`'s `fmt_debug` method now takes a `DebugFormatter` rather
than a standard formatter, and `DebugFormatter` has a new (but still
limited) facility for structured formatting.
- Implementations of `ExpandSyntax` need to produce output that
implements `DebugFormat`.
Unlike the highlighter changes, these changes are fairly focused in the
trace output, so these changes aren't behind a flag.
This commit should finish the `coloring_in_tokens` feature, which moves
the shape accumulator into the token stream. This allows rollbacks of
the token stream to also roll back any shapes that were added.
This commit also adds a much nicer syntax highlighter trace, which shows
all of the paths the highlighter took to arrive at a particular coloring
output. This change is fairly substantial, but really improves the
understandability of the flow. I intend to update the normal parser with
a similar tracing view.
In general, this change also fleshes out the concept of "atomic" token
stream operations.
A good next step would be to try to make the parser more
error-correcting, using the coloring infrastructure. A follow-up step
would involve merging the parser and highlighter shapes themselves.
The benefit of this is that coloring can be made atomic alongside token
stream forwarding.
I put the feature behind a flag so I can continue to iterate on it
without possibly regressing existing functionality. It's a lot of places
where the flags have to go, but I expect it to be a short-lived flag,
and the flags are fully contained in the parser.
* Moves off of draining between filters. Instead, the sink will pull on the stream, and will drain element-wise. This moves the whole stream to being lazy.
* Adds ctrl-c support and connects it into some of the key points where we pull on the stream. If a ctrl-c is detect, we immediately halt pulling on the stream and return to the prompt.
* Moves away from having a SourceMap where anchor locations are stored. Now AnchorLocation is kept directly in the Tag.
* To make this possible, split tag and span. Span is largely used in the parser and is copyable. Tag is now no longer copyable.
This commit replaces the previous naive coloring system with a coloring
system that is more aligned with the parser.
The main benefit of this change is that it allows us to use parsing
rules to decide how to color tokens.
For example, consider the following syntax:
```
$ ps | where cpu > 10
```
Ideally, we could color `cpu` like a column name and not a string,
because `cpu > 10` is a shorthand block syntax that expands to
`{ $it.cpu > 10 }`.
The way that we know that it's a shorthand block is that the `where`
command declares that its first parameter is a `SyntaxShape::Block`,
which allows the shorthand block form.
In order to accomplish this, we need to color the tokens in a way that
corresponds to their expanded semantics, which means that high-fidelity
coloring requires expansion.
This commit adds a `ColorSyntax` trait that corresponds to the
`ExpandExpression` trait. The semantics are fairly similar, with a few
differences.
First `ExpandExpression` consumes N tokens and returns a single
`hir::Expression`. `ColorSyntax` consumes N tokens and writes M
`FlatShape` tokens to the output.
Concretely, for syntax like `[1 2 3]`
- `ExpandExpression` takes a single token node and produces a single
`hir::Expression`
- `ColorSyntax` takes the same token node and emits 7 `FlatShape`s
(open delimiter, int, whitespace, int, whitespace, int, close
delimiter)
Second, `ColorSyntax` is more willing to plow through failures than
`ExpandExpression`.
In particular, consider syntax like
```
$ ps | where cpu >
```
In this case
- `ExpandExpression` will see that the `where` command is expecting a
block, see that it's not a literal block and try to parse it as a
shorthand block. It will successfully find a member followed by an
infix operator, but not a following expression. That means that the
entire pipeline part fails to parse and is a syntax error.
- `ColorSyntax` will also try to parse it as a shorthand block and
ultimately fail, but it will fall back to "backoff coloring mode",
which parsing any unidentified tokens in an unfallible, simple way. In
this case, `cpu` will color as a string and `>` will color as an
operator.
Finally, it's very important that coloring a pipeline infallibly colors
the entire string, doesn't fail, and doesn't get stuck in an infinite
loop.
In order to accomplish this, this PR separates `ColorSyntax`, which is
infallible from `FallibleColorSyntax`, which might fail. This allows the
type system to let us know if our coloring rules bottom out at at an
infallible rule.
It's not perfect: it's still possible for the coloring process to get
stuck or consume tokens non-atomically. I intend to reduce the
opportunity for those problems in a future commit. In the meantime, the
current system catches a number of mistakes (like trying to use a
fallible coloring rule in a loop without thinking about the possibility
that it will never terminate).
The main thrust of this (very large) commit is an overhaul of the
expansion system.
The parsing pipeline is:
- Lightly parse the source file for atoms, basic delimiters and pipeline
structure into a token tree
- Expand the token tree into a HIR (high-level intermediate
representation) based upon the baseline syntax rules for expressions
and the syntactic shape of commands.
Somewhat non-traditionally, nu doesn't have an AST at all. It goes
directly from the token tree, which doesn't represent many important
distinctions (like the difference between `hello` and `5KB`) directly
into a high-level representation that doesn't have a direct
correspondence to the source code.
At a high level, nu commands work like macros, in the sense that the
syntactic shape of the invocation of a command depends on the
definition of a command.
However, commands do not have the ability to perform unrestricted
expansions of the token tree. Instead, they describe their arguments in
terms of syntactic shapes, and the expander expands the token tree into
HIR based upon that definition.
For example, the `where` command says that it takes a block as its first
required argument, and the description of the block syntactic shape
expands the syntax `cpu > 10` into HIR that represents
`{ $it.cpu > 10 }`.
This commit overhauls that system so that the syntactic shapes are
described in terms of a few new traits (`ExpandSyntax` and
`ExpandExpression` are the primary ones) that are more composable than
the previous system.
The first big win of this new system is the addition of the `ColumnPath`
shape, which looks like `cpu."max ghz"` or `package.version`.
Previously, while a variable path could look like `$it.cpu."max ghz"`,
the tail of a variable path could not be easily reused in other
contexts. Now, that tail is its own syntactic shape, and it can be used
as part of a command's signature.
This cleans up commands like `inc`, `add` and `edit` as well as
shorthand blocks, which can now look like `| where cpu."max ghz" > 10`
This resolves a small integration issue that would make custom prompts problematic (if they are implemented). The approach was to use the highlighter implementation in Helper to insert colour codes to the prompt however it heavily relies on the prompt being in a specific format, ending with a `> ` sequence. However, this should really be the job of the prompt itself not the presentation layer.
For now, I've simply stripped off the additional `> ` characters and passed in just the prompt itself without slicing off the last two characters. I moved the `\x1b[m` control sequence to the prompt creation in `cli.rs` as this feels like the more logical home for controlling what the prompt looks like. I can think of better ways to do this in future but this should be a fine solution for now.
In future it would probably make sense to completely separate prompts (be it, internal or external) from this code so it can be configured as an isolated piece of code.
Bare words now represent literal file names, and globs are a different
syntax shape called "Pattern". This allows commands like `cp` to ask for
a pattern as a source and a literal file as a target.
This also means that attempting to pass a glob to a command that expects
a literal path will produce an error.
Previously, there was a single parsing rule for "bare words" that
applied to both internal and external commands.
This meant that, because `cargo +nightly` needed to work, we needed to
add `+` as a valid character in bare words.
The number of characters continued to grow, and the situation was
becoming untenable. The current strategy would eventually eat up all
syntax and make it impossible to add syntax like `@foo` to internal
commands.
This patch significantly restricts bare words and introduces a new token
type (`ExternalWord`). An `ExternalWord` expands to an error in the
internal syntax, but expands to a bare word in the external syntax.
`ExternalWords` are highlighted in grey in the shell.
At the moment the pipeline parser does not enforce
that there must be a pipe between each part of the pipeline,
which can lead to confusing behaviour or misleading errors.
This commit is more substantial than it looks: there was basically no
real support for decimals before, and that impacted values all the way
through.
I also made Size contain a decimal instead of an integer (`1.6kb` is a
reasonable thing to type), which impacted a bunch of code.
The biggest impact of this commit is that it creates many more possible
ways for valid nu types to fail to serialize as toml, json, etc. which
typically can't support the full range of Decimal (or Bigint, which I
also think we should support). This commit makes to-toml fallible, and a
similar effort is necessary for the rest of the serializations.
We also need to figure out how to clearly communicate to users what has
happened, but failing to serialize to toml seems clearly superior to me
than weird errors in basic math operations.
This commit makes it possible to force nu to treat a command as an external command by prefixing it with `^`. For example `^dir` will force `dir` to run an external command, even if `dir` is also a registered nu command.
This ensures that users don't need to leave nu just because we happened to use a command they need.
This commit adds a new token type for external commands, which, among other things, makes it pretty straight forward to syntax highlight external commands uniquely, and generally to treat them as special.
