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use nu_engine::command_prelude::*;
use nu_protocol::{Config, PipelineMetadata, Span, shell_error::generic::GenericError};
use std::fmt::Write;
#[derive(Clone)]
pub struct ViewSource;
impl Command for ViewSource {
fn name(&self) -> &str {
"view source"
}
fn description(&self) -> &str {
"View a block, module, or a definition."
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("view source")
.input_output_types(vec![(Type::Nothing, Type::String)])
.required("item", SyntaxShape::Any, "Name or block to view.")
.category(Category::Debug)
}
fn examples(&self) -> Vec<Example<'_>> {
vec![
Example {
description: "View the source of a code block.",
example: "let abc = {|| echo 'hi' }; view source $abc",
result: Some(Value::test_string("{|| echo 'hi' }")),
},
Example {
description: "View the source of a custom command.",
example: "def hi [] { echo 'Hi!' }; view source hi",
result: Some(Value::test_string("def hi [] { echo 'Hi!' }")),
},
Example {
description: "View the source of a custom command, which participates in the caller environment.",
example: "def --env foo [] { $env.BAR = 'BAZ' }; view source foo",
result: Some(Value::test_string("def --env foo [] { $env.BAR = 'BAZ' }")),
},
Example {
description: "View the source of a custom command with flags.",
example: "def --wrapped --env foo [...rest: string] { print $rest }; view source foo",
result: Some(Value::test_string(
"def --env --wrapped foo [ ...rest: string] { print $rest }",
)),
},
Example {
description: "View the source of a custom command with flags and arguments.",
example: "def test [a?:any --b:int ...rest:string] { echo 'test' }; view source test",
result: Some(Value::test_string(
"def test [ a?: any --b: int ...rest: string] { echo 'test' }",
)),
},
Example {
description: "View the source of a module.",
example: "module mod-foo { export-env { $env.FOO_ENV = 'BAZ' } }; view source mod-foo",
result: Some(Value::test_string(" export-env { $env.FOO_ENV = 'BAZ' }")),
},
Example {
description: "View the source of an alias.",
example: "alias hello = echo hi; view source hello",
result: Some(Value::test_string("echo hi")),
},
Example {
description: "View the file where a definition lives via metadata.",
example: "view source some_command | metadata",
result: None,
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
let arg: Value = call.req(engine_state, stack, 0)?;
let arg_span = arg.span();
match arg {
Value::Int { val, .. } => {
if let Some(block) =
engine_state.try_get_block(nu_protocol::BlockId::new(val as usize))
{
if let Some(span) = block.span {
let contents = engine_state.get_span_contents(span);
let src = String::from_utf8_lossy(contents).to_string();
Ok(make_output(engine_state, src, Some(span), call.head))
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view int value",
"the block does not have a viewable span",
arg_span,
)))
}
} else {
Err(ShellError::Generic(GenericError::new(
format!("Block Id {} does not exist", arg.coerce_into_string()?),
"this number does not correspond to a block",
arg_span,
)))
}
}
Value::String { val, .. } => {
if let Some(decl_id) = engine_state.find_decl(val.as_bytes(), &[]) {
// arg is a command
let decl = engine_state.get_decl(decl_id);
let sig = decl.signature();
let vec_of_required = &sig.required_positional;
let vec_of_optional = &sig.optional_positional;
let rest = &sig.rest_positional;
let vec_of_flags = &sig.named;
let type_signatures = &sig.input_output_types;
if decl.is_alias() {
if let Some(alias) = &decl.as_alias() {
let contents = String::from_utf8_lossy(
engine_state.get_span_contents(alias.wrapped_call.span),
);
Ok(make_output(
engine_state,
contents.to_string(),
Some(alias.wrapped_call.span),
call.head,
))
} else {
Ok(make_output(
engine_state,
"no alias found".to_string(),
None,
call.head,
))
}
}
// gets vector of positionals.
else if let Some(block_id) = decl.block_id() {
let block = engine_state.get_block(block_id);
if let Some(block_span) = block.span {
let contents = engine_state.get_span_contents(block_span);
// name of function
let mut final_contents = String::new();
// Collect def flags based on block and signature properties
let flags: Vec<&str> = [
block.redirect_env.then_some("--env"),
sig.allows_unknown_args.then_some("--wrapped"),
]
.into_iter()
.flatten()
.collect();
let flags_str = if flags.is_empty() {
String::new()
} else {
format!("{} ", flags.join(" "))
};
if val.contains(' ') {
let _ = write!(&mut final_contents, "def {flags_str}\"{val}\" [");
} else {
let _ = write!(&mut final_contents, "def {flags_str}{val} [");
};
if !vec_of_required.is_empty()
|| !vec_of_optional.is_empty()
|| vec_of_flags.len() != 1
|| rest.is_some()
{
final_contents.push(' ');
}
for n in vec_of_required {
let _ = write!(&mut final_contents, "{}: {} ", n.name, n.shape);
// positional arguments
}
for n in vec_of_optional {
if let Some(s) = n.default_value.clone() {
let _ = write!(
&mut final_contents,
"{}: {} = {} ",
n.name,
n.shape,
s.to_expanded_string(" ", &Config::default())
);
} else {
let _ =
write!(&mut final_contents, "{}?: {} ", n.name, n.shape);
}
}
for n in vec_of_flags {
// skip adding the help flag
if n.long == "help" {
continue;
}
let _ = write!(&mut final_contents, "--{}", n.long);
if let Some(short) = n.short {
let _ = write!(&mut final_contents, "(-{short})");
}
if let Some(arg) = &n.arg {
let _ = write!(&mut final_contents, ": {arg}");
}
final_contents.push(' ');
}
if let Some(rest_arg) = rest {
let _ = write!(
&mut final_contents,
"...{}:{}",
rest_arg.name, rest_arg.shape
);
}
let len = type_signatures.len();
if len != 0 {
final_contents.push_str("]: [");
let mut c = 0;
for (insig, outsig) in type_signatures {
c += 1;
let s = format!("{insig} -> {outsig}");
final_contents.push_str(&s);
if c != len {
final_contents.push_str(", ")
}
}
}
final_contents.push_str("] ");
final_contents.push_str(&String::from_utf8_lossy(contents));
Ok(make_output(
engine_state,
final_contents,
Some(block_span),
call.head,
))
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view string value",
"the command does not have a viewable block span",
arg_span,
)))
}
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view string decl value",
"the command does not have a viewable block",
arg_span,
)))
}
} else if let Some(module_id) = engine_state.find_module(val.as_bytes(), &[]) {
// arg is a module
let module = engine_state.get_module(module_id);
if let Some(module_span) = module.span {
let contents = engine_state.get_span_contents(module_span);
Ok(make_output(
engine_state,
String::from_utf8_lossy(contents).to_string(),
Some(module_span),
call.head,
))
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view string module value",
"the module does not have a viewable block",
arg_span,
)))
}
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view string value",
"this name does not correspond to a viewable value",
arg_span,
)))
}
}
value => {
if let Ok(closure) = value.as_closure() {
let block = engine_state.get_block(closure.block_id);
if let Some(span) = block.span {
let contents = engine_state.get_span_contents(span);
Ok(make_output(
engine_state,
String::from_utf8_lossy(contents).to_string(),
Some(span),
call.head,
))
} else {
Ok(make_output(
engine_state,
"<internal command>".to_string(),
None,
call.head,
))
}
} else {
Err(ShellError::Generic(GenericError::new(
"Cannot view value",
"this value cannot be viewed",
arg_span,
)))
}
}
}
}
}
// Helper function to find the file path associated with a given span, if any.
fn file_for_span(engine_state: &EngineState, span: Span) -> Option<String> {
engine_state
.files()
.find(|f| f.covered_span.contains_span(span))
.map(|f| f.name.to_string())
}
// Helper function to wrap source text into a string value and record the file path in
// datasource metadata when available
fn make_output(
engine_state: &EngineState,
src: String,
span_opt: Option<Span>,
call_span: Span,
) -> PipelineData {
let pd = Value::string(src, call_span).into_pipeline_data();
let mut metadata = PipelineMetadata {
content_type: Some("application/x-nuscript".into()),
..Default::default()
};
if let Some(span) = span_opt
&& let Some(fname) = file_for_span(engine_state, span)
{
metadata.data_source = nu_protocol::DataSource::FilePath(std::path::PathBuf::from(fname));
}
pd.set_metadata(Some(metadata))
}