use nu_engine::command_prelude::*;
use nu_parser::{flatten_block, parse};
use nu_protocol::{engine::StateWorkingSet, record};
use serde_json::{json, Value as JsonValue};
#[derive(Clone)]
pub struct Ast;
impl Command for Ast {
fn name(&self) -> &str {
"ast"
}
fn description(&self) -> &str {
"Print the abstract syntax tree (ast) for a pipeline."
}
fn signature(&self) -> Signature {
Signature::build("ast")
.input_output_types(vec![
(Type::Nothing, Type::table()),
(Type::Nothing, Type::record()),
(Type::Nothing, Type::String),
])
.required(
"pipeline",
SyntaxShape::String,
"The pipeline to print the ast for.",
)
.switch("json", "Serialize to json", Some('j'))
.switch("minify", "Minify the nuon or json output", Some('m'))
.switch("flatten", "An easier to read version of the ast", Some('f'))
.allow_variants_without_examples(true)
.category(Category::Debug)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Print the ast of a string",
example: "ast 'hello'",
result: None,
},
Example {
description: "Print the ast of a pipeline",
example: "ast 'ls | where name =~ README'",
result: None,
},
Example {
description: "Print the ast of a pipeline with an error",
example: "ast 'for x in 1..10 { echo $x '",
result: None,
},
Example {
description:
"Print the ast of a pipeline with an error, as json, in a nushell table",
example: "ast 'for x in 1..10 { echo $x ' --json | get block | from json",
result: None,
},
Example {
description: "Print the ast of a pipeline with an error, as json, minified",
example: "ast 'for x in 1..10 { echo $x ' --json --minify",
result: None,
},
Example {
description: "Print the ast of a string flattened",
example: r#"ast "'hello'" --flatten"#,
result: Some(Value::test_list(vec![Value::test_record(record! {
"content" => Value::test_string("'hello'"),
"shape" => Value::test_string("shape_string"),
"span" => Value::test_record(record! {
"start" => Value::test_int(0),
"end" => Value::test_int(7),}),
})])),
},
Example {
description: "Print the ast of a string flattened, as json, minified",
example: r#"ast "'hello'" --flatten --json --minify"#,
result: Some(Value::test_string(
r#"[{"content":"'hello'","shape":"shape_string","span":{"start":0,"end":7}}]"#,
)),
},
Example {
description: "Print the ast of a pipeline flattened",
example: r#"ast 'ls | sort-by type name -i' --flatten"#,
result: Some(Value::test_list(vec![
Value::test_record(record! {
"content" => Value::test_string("ls"),
"shape" => Value::test_string("shape_external"),
"span" => Value::test_record(record! {
"start" => Value::test_int(0),
"end" => Value::test_int(2),}),
}),
Value::test_record(record! {
"content" => Value::test_string("|"),
"shape" => Value::test_string("shape_pipe"),
"span" => Value::test_record(record! {
"start" => Value::test_int(3),
"end" => Value::test_int(4),}),
}),
Value::test_record(record! {
"content" => Value::test_string("sort-by"),
"shape" => Value::test_string("shape_internalcall"),
"span" => Value::test_record(record! {
"start" => Value::test_int(5),
"end" => Value::test_int(12),}),
}),
Value::test_record(record! {
"content" => Value::test_string("type"),
"shape" => Value::test_string("shape_string"),
"span" => Value::test_record(record! {
"start" => Value::test_int(13),
"end" => Value::test_int(17),}),
}),
Value::test_record(record! {
"content" => Value::test_string("name"),
"shape" => Value::test_string("shape_string"),
"span" => Value::test_record(record! {
"start" => Value::test_int(18),
"end" => Value::test_int(22),}),
}),
Value::test_record(record! {
"content" => Value::test_string("-i"),
"shape" => Value::test_string("shape_flag"),
"span" => Value::test_record(record! {
"start" => Value::test_int(23),
"end" => Value::test_int(25),}),
}),
])),
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
let pipeline: Spanned<String> = call.req(engine_state, stack, 0)?;
let to_json = call.has_flag(engine_state, stack, "json")?;
let minify = call.has_flag(engine_state, stack, "minify")?;
let flatten = call.has_flag(engine_state, stack, "flatten")?;
let mut working_set = StateWorkingSet::new(engine_state);
let offset = working_set.next_span_start();
let parsed_block = parse(&mut working_set, None, pipeline.item.as_bytes(), false);
if flatten {
let flat = flatten_block(&working_set, &parsed_block);
if to_json {
let mut json_val: JsonValue = json!([]);
for (span, shape) in flat {
let content =
String::from_utf8_lossy(working_set.get_span_contents(span)).to_string();
let json = json!(
{
"content": content,
"shape": shape.to_string(),
"span": {
"start": span.start.checked_sub(offset),
"end": span.end.checked_sub(offset),
},
}
);
json_merge(&mut json_val, &json);
}
let json_string = if minify {
if let Ok(json_str) = serde_json::to_string(&json_val) {
json_str
} else {
"{}".to_string()
}
} else if let Ok(json_str) = serde_json::to_string_pretty(&json_val) {
json_str
} else {
"{}".to_string()
};
Ok(Value::string(json_string, pipeline.span).into_pipeline_data())
} else {
let mut rec = vec![];
for (span, shape) in flat {
let content =
String::from_utf8_lossy(working_set.get_span_contents(span)).to_string();
let each_rec = record! {
"content" => Value::test_string(content),
"shape" => Value::test_string(shape.to_string()),
"span" => Value::test_record(record!{
"start" => Value::test_int(match span.start.checked_sub(offset) {
Some(start) => start as i64,
None => 0
}),
"end" => Value::test_int(match span.end.checked_sub(offset) {
Some(end) => end as i64,
None => 0
}),
}),
};
rec.push(Value::test_record(each_rec));
}
Ok(Value::list(rec, pipeline.span).into_pipeline_data())
}
} else {
let error_output = working_set.parse_errors.first();
let block_span = match &parsed_block.span {
Some(span) => span,
None => &pipeline.span,
};
if to_json {
let serde_block_str = if minify {
serde_json::to_string(&*parsed_block)
} else {
serde_json::to_string_pretty(&*parsed_block)
};
let block_json = match serde_block_str {
Ok(json) => json,
Err(e) => Err(ShellError::CantConvert {
to_type: "string".to_string(),
from_type: "block".to_string(),
span: *block_span,
help: Some(format!(
"Error: {e}\nCan't convert {parsed_block:?} to string"
)),
})?,
};
let serde_error_str = if minify {
serde_json::to_string(&error_output)
} else {
serde_json::to_string_pretty(&error_output)
};
let error_json = match serde_error_str {
Ok(json) => json,
Err(e) => Err(ShellError::CantConvert {
to_type: "string".to_string(),
from_type: "error".to_string(),
span: *block_span,
help: Some(format!(
"Error: {e}\nCan't convert {error_output:?} to string"
)),
})?,
};
let output_record = Value::record(
record! {
"block" => Value::string(block_json, *block_span),
"error" => Value::string(error_json, Span::test_data()),
},
pipeline.span,
);
Ok(output_record.into_pipeline_data())
} else {
let block_value = Value::string(
if minify {
format!("{parsed_block:?}")
} else {
format!("{parsed_block:#?}")
},
pipeline.span,
);
let error_value = Value::string(
if minify {
format!("{error_output:?}")
} else {
format!("{error_output:#?}")
},
pipeline.span,
);
let output_record = Value::record(
record! {
"block" => block_value,
"error" => error_value
},
pipeline.span,
);
Ok(output_record.into_pipeline_data())
}
}
}
}
fn json_merge(a: &mut JsonValue, b: &JsonValue) {
match (a, b) {
(JsonValue::Object(ref mut a), JsonValue::Object(b)) => {
for (k, v) in b {
json_merge(a.entry(k).or_insert(JsonValue::Null), v);
}
}
(JsonValue::Array(ref mut a), JsonValue::Array(b)) => {
a.extend(b.clone());
}
(JsonValue::Array(ref mut a), JsonValue::Object(b)) => {
a.extend([JsonValue::Object(b.clone())]);
}
(a, b) => {
*a = b.clone();
}
}
}
#[cfg(test)]
mod test {
#[test]
fn test_examples() {
use super::Ast;
use crate::test_examples;
test_examples(Ast {})
}
}