stack_ops.bscript

// Stack

OP_TOALTSTACK ✅
// - Puts the input onto the top of the alt stack. Removes it from the main stack.
// => OP_TOALTSTACK
// => STACK = [ 0x10 ]
// => ALT_STACK = []
// ...
// STACK = []
// ALT_STACK = [ 0x10 ]

OP_FROMALTSTACK ✅
// - Puts the input onto the top of the main stack. Removes it from the alt stack.
// => OP_TOALTSTACK
// => STACK = []
// => ALT_STACK = [ 0x10 ]
// ...
// STACK = [ 0x10 ]
// ALT_STACK = []

OP_IFDUP ✅
// - If the top stack value is not 0, duplicate it.
// => OP_IFDUP
// => STACK = [ 0x10 ]
// ...
// STACK = [ 0x10 0x10 ]

OP_DEPTH ✅
// - Puts the number of stack items onto the stack.
// => OP_DEPTH
// => STACK = [ 0x10 0x20 0x30 ]
// ...
// STACK = [ 0x03 0x10 0x20 0x30 ]

OP_DROP / [OP_2DROP] ✅
// - Removes the top stack item.
// - [Removes the top two stack items.]
// => OP_DROP
// => STACK = [ 0x10 0x20 ]
// ...
// STACK = [ 0x20 ]

OP_DUP / [OP_2DUP] / [[OP_3DUP]] ✅
// - Duplicates the top stack item.
// - [Duplicates the top two stack items (in same order)]
// - [[Duplicates the top three stack items (in same order)]]
// => OP_DUP
// => STACK = [ 0x10 0x20 ]
// ...
// STACK = [ 0x10 0x10 0x20 ]

OP_NIP ✅
// - Removes the second-to-top stack item.
// => OP_NIP
// => STACK = [ 0x20 0x10 0x30 ]
// ...
// STACK = [ 0x20 0x30 ]

OP_OVER / [OP_2OVER] ✅
// - Copies the second-to-top stack item to the top.
// - [Copies the pair of items two spaces back in the stack to the front.]
// => OP_OVER
// => STACK = [ 0x30 0x20 0x10 ]
// ...
// STACK = [ 0x20 0x30 0x20 0x10 ]

OP_PICK ✅
// - The item n back in the stack is copied to the top.
// => 1 2 3 4 2 OP_PICK
// => STACK = []
// ...
// => 2 OP_PICK
// => STACK = [ 4 3 2 1 ]
// numbering    1 2 3 4 
// => copies the 2nd item from the top of the stack to the top of the stack
// ...
// STACK = [ 3 4 3 2 1 ]

OP_ROLL ✅
// - The item n back in the stack is moved to the top.
// => 1 2 3 4 2 OP_ROLL
// => STACK = []
// ...
// => 2 OP_ROLL
// => STACK = [ 4 3 2 1 ]
// numbering    1 2 3 4 
// => moves the second element [3] to the top of the stack
// ...
// STACK = [ 3 4 2 1 ]

OP_ROT / [OP_2ROT] ✅
// - The 3rd item down the stack is moved to the top.
// - [The fifth and sixth items back are moved to the top of the stack.]
// => OP_ROT
// => STACK = [ 3 2 1 ]
// ...
// STACK = [ 1 3 2 ]

OP_SWAP / [OP_2SWAP] ✅
// - The top two items on the stack are swapped.
// - [Swaps the top two pairs of items.]
// => OP_SWAP
// => STACK = [ 1 2 3 4 ]
// ...
// STACK = [ 2 1 3 4 ]

OP_TUCK ✅
// - The item at the top of the stack is copied and inserted before the second-to-top item.
// => OP_TUCK
// => STACK = [ 1 2 3 4 ]
// ...
// STACK = [ 1 2 1 3 4 ]

OP_SIZE ✅
// - Pushes the string length of the top element of the stack (without popping it).
// => OP_SIZE
// => STACK = [ "fruit" ]
// ...
// STACK = [ 0x05 "fruit" ]