Class: Lisp::Format::Lexer

Given a format string, this class lexes it and returns directives it finds. This includes gathering parameters and modifiers for the coming directives. The necessary information to create a directive is gathered and then passed to Directives::Factory#build. Error checking is performed, so that incomplete parameters are caught and malformed modifiers are supressed.

Methods

directive have_more_input modifiers new next_char next_token params peek_char unget_char

Public Class methods

new(format)

Create a new Lexer using the given format string format.

Public Instance methods

next_token(previous)

Read the next token, given the previous one in previous, and return it. This may either be a ‘real’ directive created by Directives::Factory#build, or a Literal created in-line. If no more tokens remain, nil is returned.

Private Instance methods

directive()

Reads the directive. Raises MalformedFormatError if no input remains to read the directive from.

have_more_input()

Returns true if more input exists.

modifiers()

Read modifiers to the coming directive. Raises ModifierError if a specific modifier is given more than once.

next_char()

Reads next character in input.

params()

Read parameters to the coming directive. Raises various errors sub-classed from PositionedError when given incomplete parameters, e.g. when it runs out of input.

peek_char()

View the next character in input.

unget_char()

Unread previously read character in input.