nushell/crates/nu-protocol/src/syntax_shape.rs

use nu_source::{b, DebugDocBuilder, PrettyDebug};
use serde::{Deserialize, Serialize};

/// The syntactic shapes that values must match to be passed into a command. You can think of this as the type-checking that occurs when you call a function.
#[derive(Debug, Copy, Clone, Serialize, Deserialize)]
pub enum SyntaxShape {
    /// Any syntactic form is allowed
    Any,
    /// Strings and string-like bare words are allowed
    String,
    /// Values that can be the right hand side of a '.'
    Member,
    /// A dotted path to navigate the table
    ColumnPath,
    /// Only a numeric (integer or decimal) value is allowed
    Number,
    /// A range is allowed (eg, `1..3`)
    Range,
    /// Only an integer value is allowed
    Int,
    /// A filepath is allowed
    Path,
    /// A glob pattern is allowed, eg `foo*`
    Pattern,
    /// A block is allowed, eg `{start this thing}`
    Block,
}

impl PrettyDebug for SyntaxShape {
    /// Prepare SyntaxShape for pretty-printing
    fn pretty(&self) -> DebugDocBuilder {
        b::kind(match self {
            SyntaxShape::Any => "any shape",
            SyntaxShape::String => "string shape",
            SyntaxShape::Member => "member shape",
            SyntaxShape::ColumnPath => "column path shape",
            SyntaxShape::Number => "number shape",
            SyntaxShape::Range => "range shape",
            SyntaxShape::Int => "integer shape",
            SyntaxShape::Path => "file path shape",
            SyntaxShape::Pattern => "pattern shape",
            SyntaxShape::Block => "block shape",
        })
    }
}