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use nu_engine::CallExt;
use nu_protocol::ast::{Call, PathMember};
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Config, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape,
Value,
};
#[derive(Clone)]
pub struct Format;
impl Command for Format {
fn name(&self) -> &str {
"format"
}
fn signature(&self) -> Signature {
Signature::build("format")
.required(
"pattern",
SyntaxShape::String,
"the pattern to output. e.g.) \"{foo}: {bar}\"",
)
.category(Category::Strings)
}
fn usage(&self) -> &str {
"Format columns into a string using a simple pattern."
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let config = engine_state.get_config();
let specified_pattern: Result<Value, ShellError> = call.req(engine_state, stack, 0);
match specified_pattern {
Err(e) => Err(e),
Ok(pattern) => {
let string_pattern = pattern.as_string()?;
let ops = extract_formatting_operations(string_pattern);
format(input, &ops, call.head, config)
}
}
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Print filenames with their sizes",
example: "ls | format '{name}: {size}'",
result: None,
},
Example {
description: "Print elements from some columns of a table",
example: "echo [[col1, col2]; [v1, v2] [v3, v4]] | format '{col2}'",
result: Some(Value::List {
vals: vec![Value::test_string("v2"), Value::test_string("v4")],
span: Span::test_data(),
}),
},
]
}
}
#[derive(Debug)]
enum FormatOperation {
FixedText(String),
ValueFromColumn(String),
}
fn extract_formatting_operations(input: String) -> Vec<FormatOperation> {
let mut output = vec![];
let mut characters = input.chars();
'outer: loop {
let mut before_bracket = String::new();
for ch in &mut characters {
if ch == '{' {
break;
}
before_bracket.push(ch);
}
if !before_bracket.is_empty() {
output.push(FormatOperation::FixedText(before_bracket.to_string()));
}
let mut column_name = String::new();
for ch in &mut characters {
if ch == '}' {
break;
}
column_name.push(ch);
}
if !column_name.is_empty() {
output.push(FormatOperation::ValueFromColumn(column_name.clone()));
}
if before_bracket.is_empty() && column_name.is_empty() {
break 'outer;
}
}
output
}
fn format(
input_data: PipelineData,
format_operations: &[FormatOperation],
span: Span,
config: &Config,
) -> Result<PipelineData, ShellError> {
let data_as_value = input_data.into_value(span);
match data_as_value {
Value::Record { .. } => {
match format_record(format_operations, &data_as_value, span, config) {
Ok(value) => Ok(PipelineData::Value(Value::string(value, span), None)),
Err(value) => Err(value),
}
}
Value::List { vals, .. } => {
let mut list = vec![];
for val in vals.iter() {
match val {
Value::Record { .. } => {
match format_record(format_operations, val, span, config) {
Ok(value) => {
list.push(Value::string(value, span));
}
Err(value) => {
return Err(value);
}
}
}
_ => {
return Err(ShellError::UnsupportedInput(
"Input data is not supported by this command.".to_string(),
span,
))
}
}
}
Ok(PipelineData::ListStream(
ListStream::from_stream(list.into_iter(), None),
None,
))
}
_ => Err(ShellError::UnsupportedInput(
"Input data is not supported by this command.".to_string(),
span,
)),
}
}
fn format_record(
format_operations: &[FormatOperation],
data_as_value: &Value,
span: Span,
config: &Config,
) -> Result<String, ShellError> {
let mut output = String::new();
for op in format_operations {
match op {
FormatOperation::FixedText(s) => output.push_str(s.as_str()),
FormatOperation::ValueFromColumn(col_name) => {
match data_as_value
.clone()
.follow_cell_path(&[PathMember::String {
val: col_name.clone(),
span,
}]) {
Ok(value_at_column) => {
output.push_str(value_at_column.into_string(", ", config).as_str())
}
Err(se) => return Err(se),
}
}
}
}
Ok(output)
}
#[cfg(test)]
mod test {
#[test]
fn test_examples() {
use super::Format;
use crate::test_examples;
test_examples(Format {})
}
}