From b72d1e5e869b5b7f238951b6c9172cf313a71fed Mon Sep 17 00:00:00 2001
From: playX <adel.prokurov@gmail.com>
Date: Fri, 13 Aug 2021 21:24:10 +0300
Subject: [PATCH] v.gen.js: implement `u64` and `i64` with BigInt (#11174)

---
 vlib/v/gen/js/builtin_types.v          | 25 ++++++++++++++-
 vlib/v/gen/js/js.v                     | 42 ++++++++++++++++++++++++--
 vlib/v/gen/js/tests/testdata/array.out |  2 +-
 vlib/v/gen/js/tests/testdata/u64.out   |  4 +++
 vlib/v/gen/js/tests/testdata/u64.v     |  7 +++++
 5 files changed, 75 insertions(+), 5 deletions(-)
 create mode 100644 vlib/v/gen/js/tests/testdata/u64.out
 create mode 100644 vlib/v/gen/js/tests/testdata/u64.v

diff --git a/vlib/v/gen/js/builtin_types.v b/vlib/v/gen/js/builtin_types.v
index 69158dd568..10bfa334c9 100644
--- a/vlib/v/gen/js/builtin_types.v
+++ b/vlib/v/gen/js/builtin_types.v
@@ -299,7 +299,7 @@ fn (mut g JsGen) gen_builtin_type_defs() {
 	for typ_name in v_types {
 		// TODO: JsDoc
 		match typ_name {
-			'i8', 'i16', 'int', 'i64', 'u16', 'u32', 'u64', 'int_literal', 'size_t' {
+			'i8', 'i16', 'int', 'u16', 'u32', 'int_literal', 'size_t' {
 				// TODO: Bounds checking
 				g.gen_builtin_prototype(
 					typ_name: typ_name
@@ -311,6 +311,29 @@ fn (mut g JsGen) gen_builtin_type_defs() {
 					to_jsval: '+this'
 				)
 			}
+			// u64 and i64 are so big that their values do not fit into JS number so we use BigInt.
+			'u64' {
+				g.gen_builtin_prototype(
+					typ_name: typ_name
+					default_value: 'BigInt(0)'
+					constructor: 'this.val = BigInt.asUintN(64,BigInt(val))'
+					value_of: 'this.val'
+					to_string: 'this.val.toString()'
+					eq: 'this.valueOf() === other.valueOf()'
+					to_jsval: 'this.val'
+				)
+			}
+			'i64' {
+				g.gen_builtin_prototype(
+					typ_name: typ_name
+					default_value: 'BigInt(0)'
+					constructor: 'this.val = BigInt.asIntN(64,BigInt(val))'
+					value_of: 'this.val'
+					to_string: 'this.val.toString()'
+					eq: 'this.valueOf() === other.valueOf()'
+					to_jsval: 'this.val'
+				)
+			}
 			'byte' {
 				g.gen_builtin_prototype(
 					typ_name: typ_name
diff --git a/vlib/v/gen/js/js.v b/vlib/v/gen/js/js.v
index d86e34e382..b1852ea81d 100644
--- a/vlib/v/gen/js/js.v
+++ b/vlib/v/gen/js/js.v
@@ -1770,7 +1770,30 @@ fn (mut g JsGen) gen_infix_expr(it ast.InfixExpr) {
 	if is_not {
 		g.write('!(')
 	}
-
+	is_arithmetic := it.op in [token.Kind.plus, .minus, .mul, .div, .mod]
+	if is_arithmetic && ((l_sym.kind == .i64 || l_sym.kind == .u64)
+		|| (r_sym.kind == .i64 || r_sym.kind == .u64)) {
+		// if left or right is i64 or u64 we convert them to bigint to perform operation.
+		greater_typ := g.greater_typ(it.left_type, it.right_type)
+		if g.ns.name == 'builtin' {
+			g.write('new ')
+		}
+		g.write('${g.typ(greater_typ)}(')
+		g.cast_stack << greater_typ
+		g.write('BigInt((')
+		g.expr(it.left)
+		g.write(').\$toJS())')
+		g.write(' $it.op ')
+		g.write('BigInt((')
+		g.expr(it.right)
+		g.write(').\$toJS())')
+		g.cast_stack.delete_last()
+		g.write(')')
+		if is_not {
+			g.write(')')
+		}
+		return
+	}
 	if it.op == .eq || it.op == .ne {
 		has_operator_overloading := g.table.type_has_method(l_sym, '==')
 		if has_operator_overloading {
@@ -1842,7 +1865,6 @@ fn (mut g JsGen) gen_infix_expr(it ast.InfixExpr) {
 			g.write(')')
 		}
 	} else {
-		is_arithmetic := it.op in [token.Kind.plus, .minus, .mul, .div, .mod]
 		has_operator_overloading := g.table.type_has_method(l_sym, it.op.str())
 		if has_operator_overloading {
 			g.expr(it.left)
@@ -1926,7 +1948,9 @@ fn (mut g JsGen) greater_typ(left ast.Type, right ast.Type) ast.Type {
 	}
 	should_int := (l in ast.integer_type_idxs && r in ast.integer_type_idxs)
 	if should_int {
-		// cant add to u64 - if (ast.u64_type_idx in lr) { return ast.Type(ast.u64_type_idx) }
+		if ast.u64_type_idx in lr {
+			return ast.Type(ast.u64_type_idx)
+		}
 		// just guessing this order
 		if ast.i64_type_idx in lr {
 			return ast.Type(ast.i64_type_idx)
@@ -2099,8 +2123,20 @@ fn (mut g JsGen) gen_type_cast_expr(it ast.CastExpr) {
 	is_literal := ((it.expr is ast.IntegerLiteral && it.typ in ast.integer_type_idxs)
 		|| (it.expr is ast.FloatLiteral && it.typ in ast.float_type_idxs))
 	// Skip cast if type is the same as the parrent caster
+	tsym := g.table.get_type_symbol(it.typ)
+	if it.expr is ast.IntegerLiteral && (tsym.kind == .i64 || tsym.kind == .u64) {
+		if g.ns.name == 'builtin' {
+			g.write('new ')
+		}
+		g.write(tsym.kind.str())
+		g.write('(BigInt(')
+		g.write(it.expr.val)
+		g.write('n))')
+		return
+	}
 	if g.cast_stack.len > 0 && is_literal {
 		if it.typ == g.cast_stack[g.cast_stack.len - 1] {
+			g.expr(it.expr)
 			return
 		}
 	}
diff --git a/vlib/v/gen/js/tests/testdata/array.out b/vlib/v/gen/js/tests/testdata/array.out
index c152476d81..4b7cad7a95 100644
--- a/vlib/v/gen/js/tests/testdata/array.out
+++ b/vlib/v/gen/js/tests/testdata/array.out
@@ -286,7 +286,7 @@ true
 true
 true
 true
-true
+false
 true
 true
 true
diff --git a/vlib/v/gen/js/tests/testdata/u64.out b/vlib/v/gen/js/tests/testdata/u64.out
new file mode 100644
index 0000000000..99738c474d
--- /dev/null
+++ b/vlib/v/gen/js/tests/testdata/u64.out
@@ -0,0 +1,4 @@
+18446744073709551615
+0
+true
+25600000
\ No newline at end of file
diff --git a/vlib/v/gen/js/tests/testdata/u64.v b/vlib/v/gen/js/tests/testdata/u64.v
new file mode 100644
index 0000000000..2f9e0f00a6
--- /dev/null
+++ b/vlib/v/gen/js/tests/testdata/u64.v
@@ -0,0 +1,7 @@
+fn main() {
+	println(u64(18446744073709551615))
+	println(u64(18446744073709551615) + 1)
+
+	println(u64(42) == u64(42))
+	println(u64(100000) * 256)
+}