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Serializer.dfy
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Serializer.dfy
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/*******************************************************************************
* Copyright by the contributors to the Dafny Project
* SPDX-License-Identifier: MIT
*******************************************************************************/
/**
Implements high-level serialization (JSON values to utf-8 bytes).
*/
module Std.JSON.Serializer {
import Collections.Seq
import Math
import Values
import Spec
import opened Wrappers
import opened BoundedInts
import opened Strings
import opened Errors
import opened DynamicArray
import opened Grammar
import opened Utils.Views.Core
import ByteStrConversion
type Result<+T> = SerializationResult<T>
type bytes = seq<uint8>
type bytes32 = bs: bytes | |bs| < TWO_TO_THE_32
type string32 = s: string | |s| < TWO_TO_THE_32
function Bool(b: bool): jbool {
View.OfBytes(if b then TRUE else FALSE)
}
function CheckLength<T>(s: seq<T>, err: SerializationError): Outcome<SerializationError> {
Outcome.Need(|s| < TWO_TO_THE_32, err)
}
function String(str: string): Result<jstring> {
var bs :- Spec.EscapeToUTF8(str);
var o := CheckLength(bs, StringTooLong(str));
if o.Pass? then
Success(Grammar.JString(Grammar.DOUBLEQUOTE, View.OfBytes(bs), Grammar.DOUBLEQUOTE))
else
Failure(o.error)
}
function Sign(n: int): jminus {
View.OfBytes(if n < 0 then ['-' as byte] else [])
}
const DIGITS := ByteStrConversion.chars
const MINUS := '-' as byte
function Int'(n: int): (str: bytes)
ensures forall c | c in str :: c in DIGITS || c == MINUS
{
ByteStrConversion.OfInt(n, MINUS)
}
function Int(n: int): Result<View> {
var bs := Int'(n);
var o := CheckLength(bs, IntTooLarge(n));
if o.Pass? then
Success(View.OfBytes(bs))
else
Failure(o.error)
}
function {:isolate_assertions} {:resource_limit 1000000} Number(dec: Values.Decimal): Result<jnumber> {
var minus: jminus := Sign(dec.n);
var num: jnum :- Int(Math.Abs(dec.n));
var frac: Maybe<jfrac> := Empty();
var exp: Maybe<jexp> :-
if dec.e10 == 0 then
Success(Empty())
else
var e: je := View.OfBytes(['e' as byte]);
var sign: jsign := Sign(dec.e10);
var num: jnum :- Int(Math.Abs(dec.e10));
Success(NonEmpty(JExp(e, sign, num)));
Success(JNumber(minus, num, Empty, exp))
}
function MkStructural<T>(v: T): Structural<T> {
Structural(EMPTY, v, EMPTY)
}
const COLON: Structural<jcolon> :=
MkStructural(Grammar.COLON)
function KeyValue(kv: (string, Values.JSON)): Result<jKeyValue> {
var k :- String(kv.0);
var v :- Value(kv.1);
Success(Grammar.KeyValue(k, COLON, v))
}
function MkSuffixedSequence<D, S>(ds: seq<D>, suffix: Structural<S>, start: nat := 0)
: SuffixedSequence<D, S>
decreases |ds| - start
{
if start >= |ds| then []
else if start == |ds| - 1 then [Suffixed(ds[start], Empty)]
else [Suffixed(ds[start], NonEmpty(suffix))] + MkSuffixedSequence(ds, suffix, start + 1)
}
const COMMA: Structural<jcomma> :=
MkStructural(Grammar.COMMA)
function Object(obj: seq<(string, Values.JSON)>): Result<jobject> {
var items :- Seq.MapWithResult(v requires v in obj => KeyValue(v), obj);
Success(Bracketed(MkStructural(LBRACE),
MkSuffixedSequence(items, COMMA),
MkStructural(RBRACE)))
}
function Array(arr: seq<Values.JSON>): Result<jarray> {
var items :- Seq.MapWithResult(v requires v in arr => Value(v), arr);
Success(Bracketed(MkStructural(LBRACKET),
MkSuffixedSequence(items, COMMA),
MkStructural(RBRACKET)))
}
function Value(js: Values.JSON): Result<Grammar.Value> {
match js
case Null => Success(Grammar.Null(View.OfBytes(NULL)))
case Bool(b) => Success(Grammar.Bool(Bool(b)))
case String(str) => var s :- String(str); Success(Grammar.String(s))
case Number(dec) => var n :- Number(dec); Success(Grammar.Number(n))
case Object(obj) => var o :- Object(obj); Success(Grammar.Object(o))
case Array(arr) => var a :- Array(arr); Success(Grammar.Array(a))
}
function JSON(js: Values.JSON): Result<Grammar.JSON> {
var val :- Value(js);
Success(MkStructural(val))
}
}