class Cell

S-Expression Cell, implements the AST interface.

Consists of a head expression and any number of tail expressions (both AST nodes), a Tag, and optionally the internal whitespace as parsed.

index

members

• cell:head()  – get the head of the cell.
• cell:tail()  – get the tail of the cell.
• cell.tag  – the parsed Tag.
• cell.children  – sequence of child AST Nodes
• cell.whitespace  – optional sequence of whitespace segments.

static functions

• Cell.parse([tag], parts)  – parse a Cell (for parsing with Lpeg).
• Cell.parse_root(parts)  – parse a root Cell (for parsing with Lpeg).

ast interface

• cell:eval(scope)  – evaluate this Cell.
• cell:clone(parent)  – create a clone with its own identity.
• cell:stringify([depth])  – stringify this Cell.

details

members

• cell:head()  – get the head of the cell.

  returns:

  1. (AST)
• cell:tail()  – get the tail of the cell.

  returns:

  1. ({AST,...})
• cell.tag  – the parsed Tag.
  • tag (Tag)
• cell.children  – sequence of child AST Nodes
  • children ({AST,...})
• cell.whitespace  – optional sequence of whitespace segments.
  If set, whitespace[i] is the whitespace between children[i] and children[i+1], or the closing parenthesis of this Cell. whitespace[0] is the space between the opening parenthesis and children[1].

  • whitespace (optional {string,...})

static functions

• Cell.parse([tag], parts)  – parse a Cell (for parsing with Lpeg).

  parameters:

  • tag (Tag) (optional)
  • parts (table)

  returns:

  1. (Cell)
• Cell.parse_root(parts)  – parse a root Cell (for parsing with Lpeg).
  Root-Cells are at the root of an ALV document. They have an implicit head of ‘do’ and a [0] tag.

  parameters:

  • parts (table)

  returns:

  1. (Cell)

ast interface

• cell:eval(scope)  – evaluate this Cell.
  AST:evaluates the head of the expression, and finds the appropriate Builtin to invoke:

  • if head is an opdef, use invoke.op_invoke
  • if head is a fndef, use invoke.fn_invoke
  • if head is a builtin, unwrap it

  then calls Builtin:eval_cell on it.

  parameters:

  • scope (Scope): the scope to evaluate in

  returns:

  1. (Result): the evaluation result
• cell:clone(parent)  – create a clone with its own identity.
  creates a clone of this Cell with its own identity by prepending a parent to tag and cloning all child expressions recursively.

  parameters:

  • parent (Tag)

  returns:

  1. (Cell)
• cell:stringify([depth])  – stringify this Cell.
  if depth is passed, does not faithfully recreate the original string but rather create useful debug output.

  parameters:

  • depth (int): the maximum depth, defaults to infinite (optional)

  returns:

  1. (string): the exact string this Cell was parsed from, unless @tag changed