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# Wrappers around file system primitives that take a 'resources' object and
# are thus easier to test.
#
# - start-reading - asynchronously open a file, returning a channel source for
# receiving the results
# - start-writing - asynchronously open a file, returning a channel sink for
# the data to write
# - slurp - synchronously read from a file
# - dump - synchronously write to a file
container resources [
lock:bool
data:&:@:resource
]
container resource [
name:text
contents:text
]
def start-reading resources:&:resources, filename:text -> contents:&:source:char, error?:bool [
local-scope
load-inputs
error? <- copy false
{
break-unless resources
# fake file system
contents, error? <- start-reading-from-fake-resource resources, filename
return
}
# real file system
file:num <- $open-file-for-reading filename
return-unless file, null/no-contents, true/error
contents:&:source:char, sink:&:sink:char <- new-channel 30
start-running receive-from-file file, sink
]
def slurp resources:&:resources, filename:text -> contents:text, error?:bool [
local-scope
load-inputs
source:&:source:char, error?:bool <- start-reading resources, filename
return-if error?, null/no-contents
buf:&:buffer:char <- new-buffer 30/capacity
{
c:char, done?:bool, source <- read source
break-if done?
buf <- append buf, c
loop
}
contents <- buffer-to-array buf
]
def start-reading-from-fake-resource resources:&:resources, resource:text -> contents:&:source:char, error?:bool [
local-scope
load-inputs
error? <- copy false
i:num <- copy 0
data:&:@:resource <- get *resources, data:offset
len:num <- length *data
{
done?:bool <- greater-or-equal i, len
break-if done?
tmp:resource <- index *data, i
i <- add i, 1
curr-resource:text <- get tmp, name:offset
found?:bool <- equal resource, curr-resource
loop-unless found?
contents:&:source:char, sink:&:sink:char <- new-channel 30
curr-contents:text <- get tmp, contents:offset
start-running receive-from-text curr-contents, sink
return
}
return null/no-such-resource, true/error-found
]
def receive-from-file file:num, sink:&:sink:char -> sink:&:sink:char [
local-scope
load-inputs
{
c:char, eof?:bool <- $read-from-file file
break-if eof?
sink <- write sink, c
loop
}
sink <- close sink
file <- $close-file file
]
def receive-from-text contents:text, sink:&:sink:char -> sink:&:sink:char [
local-scope
load-inputs
i:num <- copy 0
len:num <- length *contents
{
done?:bool <- greater-or-equal i, len
break-if done?
c:char <- index *contents, i
sink <- write sink, c
i <- add i, 1
loop
}
sink <- close sink
]
def start-writing resources:&:resources, filename:text -> sink:&:sink:char, routine-id:num, error?:bool [
local-scope
load-inputs
error? <- copy false
source:&:source:char, sink:&:sink:char <- new-channel 30
{
break-unless resources
# fake file system
routine-id <- start-running transmit-to-fake-resource resources, filename, source
return
}
# real file system
file:num <- $open-file-for-writing filename
return-unless file, null/sink, 0/routine-id, true/error
{
break-if file
msg:text <- append [no such file: ] filename
assert file, msg
}
routine-id <- start-running transmit-to-file file, source
]
def dump resources:&:resources, filename:text, contents:text -> resources:&:resources, error?:bool [
local-scope
load-inputs
# todo: really create an empty file
return-unless contents, resources, false/no-error
sink-file:&:sink:char, write-routine:num, error?:bool <- start-writing resources, filename
return-if error?
i:num <- copy 0
len:num <- length *contents
{
done?:bool <- greater-or-equal i, len
break-if done?
c:char <- index *contents, i
sink-file <- write sink-file, c
i <- add i, 1
loop
}
close sink-file
# make sure to wait for the file to be actually written to disk
# (Mu practices structured concurrency: http://250bpm.com/blog:71)
wait-for-routine write-routine
]
def transmit-to-file file:num, source:&:source:char -> source:&:source:char [
local-scope
load-inputs
{
c:char, done?:bool, source <- read source
break-if done?
$write-to-file file, c
loop
}
file <- $close-file file
]
def transmit-to-fake-resource resources:&:resources, filename:text, source:&:source:char -> resources:&:resources, source:&:source:char [
local-scope
load-inputs
lock:location <- get-location *resources, lock:offset
wait-for-reset-then-set lock
# compute new file contents
buf:&:buffer:char <- new-buffer 30
{
c:char, done?:bool, source <- read source
break-if done?
buf <- append buf, c
loop
}
contents:text <- buffer-to-array buf
new-resource:resource <- merge filename, contents
# write to resources
curr-filename:text <- copy null
data:&:@:resource <- get *resources, data:offset
# replace file contents if it already exists
i:num <- copy 0
len:num <- length *data
{
done?:bool <- greater-or-equal i, len
break-if done?
tmp:resource <- index *data, i
curr-filename <- get tmp, name:offset
found?:bool <- equal filename, curr-filename
{
break-unless found?
put-index *data, i, new-resource
jump +unlock-and-exit
}
i <- add i, 1
loop
}
# if file didn't already exist, make room for it
new-len:num <- add len, 1
new-data:&:@:resource <- new resource:type, new-len
put *resources, data:offset, new-data
# copy over old files
i:num <- copy 0
{
done?:bool <- greater-or-equal i, len
break-if done?
tmp:resource <- index *data, i
put-index *new-data, i, tmp
}
# write new file
put-index *new-data, len, new-resource
+unlock-and-exit
reset lock
]
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