use nu_engine::command_prelude::*;
use nu_protocol::{Config, DataSource, PipelineMetadata};
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 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();
let source = 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);
Ok(Value::string(String::from_utf8_lossy(contents), call.head)
.into_pipeline_data())
} else {
Err(ShellError::GenericError {
error: "Cannot view int value".to_string(),
msg: "the block does not have a viewable span".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
} else {
Err(ShellError::GenericError {
error: format!("Block Id {} does not exist", arg.coerce_into_string()?),
msg: "this number does not correspond to a block".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
}
Value::String { val, .. } => {
if let Some(decl_id) = engine_state.find_decl(val.as_bytes(), &[]) {
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(Value::string(contents, call.head).into_pipeline_data())
} else {
Ok(Value::string("no alias found", call.head).into_pipeline_data())
}
}
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);
let mut final_contents = String::new();
if val.contains(' ') {
let _ = write!(&mut final_contents, "def \"{val}\" [");
} else {
let _ = write!(&mut final_contents, "def {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);
}
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 {
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(Value::string(final_contents, call.head).into_pipeline_data())
} else {
Err(ShellError::GenericError {
error: "Cannot view string value".to_string(),
msg: "the command does not have a viewable block span".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
} else {
Err(ShellError::GenericError {
error: "Cannot view string decl value".to_string(),
msg: "the command does not have a viewable block".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
} else if let Some(module_id) = engine_state.find_module(val.as_bytes(), &[]) {
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(Value::string(String::from_utf8_lossy(contents), call.head)
.into_pipeline_data())
} else {
Err(ShellError::GenericError {
error: "Cannot view string module value".to_string(),
msg: "the module does not have a viewable block".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
} else {
Err(ShellError::GenericError {
error: "Cannot view string value".to_string(),
msg: "this name does not correspond to a viewable value".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
}
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(Value::string(String::from_utf8_lossy(contents), call.head)
.into_pipeline_data())
} else {
Ok(Value::string("<internal command>", call.head).into_pipeline_data())
}
} else {
Err(ShellError::GenericError {
error: "Cannot view value".to_string(),
msg: "this value cannot be viewed".to_string(),
span: Some(arg_span),
help: None,
inner: vec![],
})
}
}
};
source.map(|x| {
x.set_metadata(Some(PipelineMetadata {
data_source: DataSource::None,
content_type: Some("application/x-nuscript".into()),
}))
})
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "View the source of a code block",
example: r#"let abc = {|| echo 'hi' }; view source $abc"#,
result: Some(Value::test_string("{|| echo 'hi' }")),
},
Example {
description: "View the source of a custom command",
example: r#"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: r#"def --env foo [] { $env.BAR = 'BAZ' }; view source foo"#,
result: Some(Value::test_string("def foo [] { $env.BAR = 'BAZ' }")),
},
Example {
description: "View the source of a custom command with flags and arguments",
example: r#"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: r#"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: r#"alias hello = echo hi; view source hello"#,
result: Some(Value::test_string("echo hi")),
},
]
}
}