parsley/parsley/registers

registers

object registers

This module contains all the functionality and operations for using and manipulating registers.

This module contains all the functionality and operations for using and manipulating registers.

Since

2.2.0

class Object
trait Matchable
class Any

Type members

Classlikes

class Reg[A]

This class is used to index registers within the mutable state. Currently, there are only 4 available registers, so use them wisely!

This class is used to index registers within the mutable state. Currently, there are only 4 available registers, so use them wisely!

If you need more than four registers but know that they will be used at different times you can rename your register, as long as they point to the same reference. You may find the Parsley[A].cast[B: ClassTag]: Parsley[B] combinator useful to change the type of a Reg[Any].

Since

2.2.0

Note

It is undefined behaviour to use a register in multiple different independent parsers. You should be careful to parameterise the registers in shared parsers and allocate fresh ones for each "top-level" parser you will run.

Companion
object
object Reg
Companion
class

Value members

Concrete methods

def get[S](r: Reg[S]): Parsley[S]

Consumes no input and returns the value stored in one of the parser registers.

Consumes no input and returns the value stored in one of the parser registers.

Type Params
S

The type of the value in register r (this will result in a runtime type-check)

Value Params
r

The index of the register to collect from

Returns

The value stored in register r of type S

Since

2.2.0

Note

There are only 4 registers at present.

def gets[S, A](r: Reg[S], f: S => A): Parsley[A]

Consumes no input and returns the value stored in one of the parser registers after applying a function.

Consumes no input and returns the value stored in one of the parser registers after applying a function.

Type Params
A

The desired result type

S

The type of the value in register r (this will result in a runtime type-check)

Value Params
f

The function used to transform the value in the register

r

The index of the register to collect from

Returns

The value stored in register r applied to f

Since

2.2.0

Note

There are only 4 registers at present.

def gets[S, A](r: Reg[S], pf: Parsley[S => A]): Parsley[A]

Returns the value stored in one of the parser registers after applying a function obtained from given parser.

Returns the value stored in one of the parser registers after applying a function obtained from given parser.

Type Params
A

The desired result type

S

The type of the value in register r (this will result in a runtime type-check)

Value Params
pf

The parser which provides the function to transform values

r

The index of the register to collect from

Returns

The value stored in register r applied to f from pf

Since

2.2.0

Note

There are only 4 registers at present. The value is fetched after pf is executed

def local[R, A](r: Reg[R], x: R, p: => Parsley[A]): Parsley[A]

For the duration of parser p the state stored in register r is instead set to x. The change is undone after p has finished.

For the duration of parser p the state stored in register r is instead set to x. The change is undone after p has finished.

Value Params
p

The parser to execute with the adjusted state

r

The index of the register to modify

x

The value to place in the register r

Returns

The parser that performs p with the modified state

Since

2.2.0

Note

There are only 4 registers at present.

def local[R, A](r: Reg[R], p: => Parsley[R], q: => Parsley[A]): Parsley[A]

For the duration of parser q the state stored in register r is instead set to the return value of p. The change is undone after q has finished.

For the duration of parser q the state stored in register r is instead set to the return value of p. The change is undone after q has finished.

Value Params
p

The parser whose return value is placed in register r

q

The parser to execute with the adjusted state

r

The index of the register to modify

Returns

The parser that performs q with the modified state

Since

2.2.0

Note

There are only 4 registers at present.

def local[R, A](r: Reg[R], f: R => R, p: => Parsley[A]): Parsley[A]

For the duration of parser p the state stored in register r is instead modified with f. The change is undone after p has finished.

For the duration of parser p the state stored in register r is instead modified with f. The change is undone after p has finished.

Value Params
f

The function used to modify the value in register r

p

The parser to execute with the adjusted state

r

The index of the register to modify

Returns

The parser that performs p with the modified state

Since

2.2.0

Note

There are only 4 registers at present.

def modify[S](r: Reg[S], f: S => S): Parsley[Unit]

Modifies the value contained in register r using function f.

Modifies the value contained in register r using function f.

Type Params
S

The type of value currently assumed to be in the register

Value Params
f

The function used to modify the register

r

The index of the register to modify

Since

2.2.0

Note

There are only 4 registers at present.

def put[S](r: Reg[S], x: S): Parsley[Unit]

Consumes no input and places the value x into register r.

Consumes no input and places the value x into register r.

Value Params
r

The index of the register to place the value in

x

The value to place in the register

Since

2.2.0

Note

There are only 4 registers at present.

def put[S](r: Reg[S], p: => Parsley[S]): Parsley[Unit]

Places the result of running p into register r.

Places the result of running p into register r.

Value Params
p

The parser to derive the value from

r

The index of the register to place the value in

Since

2.2.0

Note

There are only 4 registers at present.

def puts[A, S](r: Reg[S], p: => Parsley[A], f: A => S): Parsley[Unit]

Places the result of running p into register r.

Places the result of running p into register r.

Value Params
f

A function which adapts the result of p so that it can fit in r

p

The parser to derive the value from

r

The index of the register to place the value in

Since

3.0.0

Note

There are only 4 registers at present.

def rollback[A, B](reg: Reg[A], p: Parsley[B]): Parsley[B]

rollback(reg, p) will perform p, but if it fails without consuming input, any changes to the register reg will be reverted.

rollback(reg, p) will perform p, but if it fails without consuming input, any changes to the register reg will be reverted.

Value Params
p

The parser to perform

reg

The register to rollback on failure of p

Returns

The result of the parser p, if any

Since

2.2.0