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# Some useful helpers for dealing with strings
recipe string-equal [
default-space:address:space <- new location:type, 30:literal
a:address:array:character <- next-ingredient
a-len:integer <- length a:address:array:character/deref
b:address:array:character <- next-ingredient
b-len:integer <- length b:address:array:character/deref
# compare lengths
{
trace [string-equal], [comparing lengths]
length-equal?:boolean <- equal a-len:integer, b-len:integer
break-if length-equal?:boolean
reply 0:literal
}
# compare each corresponding character
trace [string-equal], [comparing characters]
i:integer <- copy 0:literal
{
done?:boolean <- greater-or-equal i:integer, a-len:integer
break-if done?:boolean
a2:character <- index a:address:array:character/deref, i:integer
b2:character <- index b:address:array:character/deref, i:integer
{
chars-match?:boolean <- equal a2:character, b2:character
break-if chars-match?:boolean
reply 0:literal
}
i:integer <- add i:integer, 1:literal
loop
}
reply 1:literal
]
scenario string-equal-reflexive [
run [
default-space:address:space <- new location:type, 30:literal
x:address:array:character <- new [abc]
3:boolean/raw <- string-equal x:address:array:character, x:address:array:character
]
memory should contain [
3 <- 1 # x == x for all x
]
]
scenario string-equal-identical [
run [
default-space:address:space <- new location:type, 30:literal
x:address:array:character <- new [abc]
y:address:array:character <- new [abc]
3:boolean/raw <- string-equal x:address:array:character, y:address:array:character
]
memory should contain [
3 <- 1 # abc == abc
]
]
scenario string-equal-distinct-lengths [
run [
default-space:address:space <- new location:type, 30:literal
x:address:array:character <- new [abc]
y:address:array:character <- new [abcd]
3:boolean/raw <- string-equal x:address:array:character, y:address:array:character
]
memory should contain [
3 <- 0 # abc != abcd
]
trace should contain [
string-equal: comparing lengths
]
trace should not contain [
string-equal: comparing characters
]
]
scenario string-equal-with-empty [
run [
default-space:address:space <- new location:type, 30:literal
x:address:array:character <- new []
y:address:array:character <- new [abcd]
3:boolean/raw <- string-equal x:address:array:character, y:address:array:character
]
memory should contain [
3 <- 0 # "" != abcd
]
]
scenario string-equal-common-lengths-but-distinct [
run [
default-space:address:space <- new location:type, 30:literal
x:address:array:character <- new [abc]
y:address:array:character <- new [abd]
3:boolean/raw <- string-equal x:address:array:character, y:address:array:character
]
memory should contain [
3 <- 0 # abc != abd
]
]
# A new type to help incrementally construct strings.
container buffer [
length:integer
data:address:array:character
]
recipe init-buffer [
default-space:address:space <- new location:type, 30:literal
result:address:buffer <- new buffer:type
len:address:integer <- get-address result:address:buffer/deref, length:offset
len:address:integer/deref <- copy 0:literal
s:address:address:array:character <- get-address result:address:buffer/deref, data:offset
capacity:integer <- next-ingredient
s:address:address:array:character/deref <- new character:type, capacity:integer
reply result:address:buffer
]
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