R: Display the abstract syntax tree

ast {lobstr} | R Documentation

## Display the abstract syntax tree

### Description

This is a useful alternative to `str()` for expression objects.

### Usage

    ast(x)

### Arguments

`x` | An expression to display. Input is automatically quoted, use `!!` to unquote if you have already captured an expression object.

### See Also

Other object inspectors: `ref()`, `sxp()`

### Examples

    # Leaves
    ast(1)
    ast(x)

    # Simple calls
    ast(f())
    ast(f(x, 1, g(), h(i())))
    ast(f()())
    ast(f(x)(y))

    ast((x + 1))

    # Displaying expression already stored in object
    x <- quote(a + b + c)
    ast(x)
    ast(!!x)

    # All operations have this same structure
    ast(if (TRUE) 3 else 4)
    ast(y <- x * 10)
    ast(function(x = 1, y = 2) { x + y } )

    # Operator precedence
    ast(1 * 2 + 3)
    ast(!1 + !1)

[Package lobstr version 1.1.2 Index]