ref: 78da203b42b5084a7664e8773f418a4730184d53
dir: /lib/json/parse.myr/
use std
use "types"
pkg json =
const parse : (str : byte[:] -> std.result(elt#, err))
const free : (j : elt# -> void)
;;
const Maxdepth = 1024
type parser = struct
str : byte[:]
depth : std.size
line : std.size
off : std.size
idx : std.size
;;
const parse = {str
var parser : parser
parser = [
.str = str,
.depth = 0,
.line = 1,
.off = 1,
.idx = 0,
]
match parseelt(&parser)
| `std.Ok j:
takespace(&parser)
if parser.idx != parser.str.len
free(j)
-> `std.Err [
.e=`Junk std.decode(parser.str[parser.idx:]),
.line=parser.line,
.off=parser.off
]
;;
-> `std.Ok j
| `std.Err e:
-> `std.Err e
;;
}
const free = {j
match j
| &(`Null): /* nothing */
| &(`Bool _): /* nothing */
| &(`Num _): /* nothing */
| &(`Str s): std.slfree(s)
| &(`Arr a):
for e : a
free(e)
;;
| &(`Obj o):
for (k, v) : o
std.slfree(k)
free(v)
;;
;;
}
const parseelt = {p
takespace(p)
match peekc(p)
| '{': -> parseobj(p)
| '[': -> parsearr(p)
| '"': -> parsestr(p)
| chr:
if matchprefix(p, "false")
-> `std.Ok std.mk(`Bool false)
elif matchprefix(p, "true")
-> `std.Ok std.mk(`Bool true)
elif matchprefix(p, "null")
-> `std.Ok std.mk(`Null)
elif std.isdigit(peekc(p)) || peekc(p) == '-'
match parsenum(p)
| `std.Some n: -> `std.Ok std.mk(`Num n)
| `std.None: -> `std.Err [.e=`Junk chr, .line=p.line, .off=p.off]
;;
else
-> `std.Err [.e=`Junk chr, .line=p.line, .off=p.off]
;;
;;
}
const parseobj = {p
var membs
var err
std.assert(takec(p) == '{', "should only enter 'obj' after '{'")
membs = [][:]
if !enter(p)
err = [.e = `Depth, .line=p.line, .off=p.off]
goto error
;;
takespace(p)
if peekc(p) == '}'
takec(p)
-> `std.Ok std.mk(`Obj membs)
;;
while peekc(p) != '}'
match member(p)
| `std.Ok m:
std.slpush(&membs, m)
takespace(p)
match takec(p)
| ',': /* nothing */
| '}': break
| std.Badchar:
err = [.e=`End, .line=p.line, .off=p.off]
goto error
| chr:
err = [.e=`Junk chr, .line=p.line, .off=p.off]
goto error
;;
| `std.Err e:
err = e
goto error
;;
;;
exit(p)
-> `std.Ok std.mk(`Obj membs)
:error
for (k, v) : membs
std.slfree(k)
free(v)
;;
std.slfree(membs)
exit(p)
-> `std.Err err
}
const member = {p
var str
takespace(p)
match jsonstr(p)
| `std.Ok s: str = s
| `std.Err e: -> `std.Err e
;;
takespace(p)
match takec(p)
| ':': /* nothing */
| chr: -> `std.Err [.e=`Junk chr, .line=p.line, .off=p.off]
;;
takespace(p)
match parseelt(p)
| `std.Ok elt:
-> `std.Ok (str, elt)
| `std.Err e:
std.slfree(str)
-> `std.Err e
;;
}
const parsearr = {p -> std.result(elt#, err)
var elts
var err
std.assert(takec(p) == '[', "should only enter 'obj' after '['\n")
elts = [][:]
if !enter(p)
err = [.e = `Depth, .line=p.line, .off=p.off]
goto error
;;
takespace(p)
if peekc(p) == ']'
takec(p)
-> `std.Ok std.mk(`Arr elts)
;;
while true
match parseelt(p)
| `std.Ok e:
std.slpush(&elts, e)
| `std.Err e:
err = e
goto error
;;
takespace(p)
match takec(p)
| ',': /* nothing */
| ']': break
| std.Badchar:
err = [.e=`End, .line=p.line, .off=p.off]
goto error
| chr:
err = [.e=`Junk chr, .line=p.line, .off=p.off]
goto error
;;
;;
exit(p)
-> `std.Ok std.mk(`Arr elts)
:error
for e : elts
free(e)
;;
std.slfree(elts)
exit(p)
-> `std.Err err
}
const parsestr = {p
match jsonstr(p)
| `std.Ok str: -> `std.Ok std.mk(`Str str)
| `std.Err e: -> `std.Err e
;;
}
const parsenum = {p
var start
var ok
start = p.idx
if peekc(p) == '-'
p.idx++
;;
if peekc(p) == '0'
p.idx++
else
ok = false
while p.idx < p.str.len
if !std.isdigit((p.str[p.idx] : char))
break
;;
ok = true
p.idx++
;;
if !ok
-> `std.None
;;
;;
if peekc(p) == '.'
ok = false
p.idx++
while p.idx < p.str.len
if !std.isdigit((p.str[p.idx] : char))
break
;;
ok = true
p.idx++
;;
if !ok
-> `std.None
;;
;;
if peekc(p) == 'e' || peekc(p) == 'E'
p.idx++
ok = false
if peekc(p) == '+' || peekc(p) == '-'
p.idx++
;;
while p.idx < p.str.len
if !std.isdigit((p.str[p.idx] : char))
break
;;
ok = true
p.idx++
;;
if !ok
-> `std.None
;;
;;
-> std.flt64parse(p.str[start:p.idx])
}
const jsonstr = {p
var sb, idx, err
sb = std.mksb()
match takec(p)
| '"': /* nothing */
| chr:
err = [.e=`Junk chr, .line=p.line, .off=p.off]
goto error
;;
while p.idx < p.str.len
match takec(p)
| '\\':
match takec(p)
| '"': std.sbputc(sb, '"')
| '\\': std.sbputc(sb, '\\')
| '/': std.sbputc(sb, '/')
| 'b': std.sbputc(sb, '\b')
| 'n': std.sbputc(sb, '\n')
| 'f': std.sbputc(sb, '\u{0c}')
| 'r': std.sbputc(sb, '\r')
| 't': std.sbputc(sb, '\t')
| 'u':
match unichar(p)
| `std.Some c: std.sbputc(sb, c)
| `std.None:
err = [.e=`Badesc 'u', .line=p.line, .off=p.off]
goto error
;;
| chr:
err = [.e=`Badesc chr, .line=p.line, .off=p.off]
goto error
;;
| '"':
-> `std.Ok std.sbfin(sb)
| std.Badchar:
err = [.e=`Junk std.Badchar, .line=p.line, .off=p.off]
goto error
| chr:
if !unescaped(chr)
err = [.e=`Junk chr, .line=p.line, .off=p.off]
goto error
;;
std.sbputc(sb, chr)
idx += std.charlen(chr)
;;
;;
err = [.e=`End, .line=p.line, .off=p.off]
:error
std.sbfree(sb)
-> `std.Err err
}
const unichar = {p
var c, i
c = 0
/* must be exactly 4 hex digits */
for i = 0; i < 4; i++
match std.charval(takec(p), 16)
| -1: -> `std.None
| n: c += n*16
;;
;;
if i == 0
-> `std.None
;;
-> `std.Some c
}
const matchprefix = {p, pfx
if std.hasprefix(p.str[p.idx:], pfx)
p.idx += pfx.len
-> true
;;
-> false
}
const unescaped = {c
-> c == 0x20 || c == 0x21 || \
(c >= 0x23 && c < 0x5b) || \
(c > 0x5d && c <= 0x10ffff)
}
const takespace = {p
while p.idx < p.str.len
match (p.str[p.idx] : char)
| ' ':
| '\t':
| '\r':
| '\n':
p.line++
p.off=1
| _:
break
;;
p.idx++
;;
}
const peekc = {p
-> std.decode(p.str[p.idx:])
}
const takec = {p
var c
if p.idx == p.str.len
-> std.Badchar
;;
c = std.decode(p.str[p.idx:])
p.idx += std.charlen(c)
p.off++
if c == '\n'
p.line++
p.off = 1
;;
-> c
}
const enter = {p
p.depth++
-> p.depth <= Maxdepth
}
const exit = {p
p.depth--
}