internal/intconv: Add

12 files changed, 142 insertions, 0 deletions

diff --git a/internal/intconv/doc.go b/internal/intconv/doc.go
new file mode 100644
index 00000000..fc1f7428
--- /dev/null
+++ b/internal/intconv/doc.go
@@ -0,0 +1,2 @@
+// Package intconv provides checked integer conversion helpers.
+package intconv
diff --git a/internal/intconv/errors.go b/internal/intconv/errors.go
new file mode 100644
index 00000000..fff2b1bc
--- /dev/null
+++ b/internal/intconv/errors.go
@@ -0,0 +1,12 @@
+package intconv
+
+import "errors"
+
+// ErrOverflow indicates that
+// a requested checked integer conversion
+// is impossible due to
+// integer overflow,
+// integer underflow,
+// unexpected negative integers,
+// or a similar situation.
+var ErrOverflow = errors.New("intconv: overflow")
diff --git a/internal/intconv/i64_i32.go b/internal/intconv/i64_i32.go
new file mode 100644
index 00000000..bcee9205
--- /dev/null
+++ b/internal/intconv/i64_i32.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// Int64ToInt32 converts v to int32, returning an error if it overflows.
+func Int64ToInt32(v int64) (int32, error) {
+	if v < math.MinInt32 || v > math.MaxInt32 {
+		return 0, ErrOverflow
+	}
+
+	return int32(v), nil
+}
diff --git a/internal/intconv/i64_u64.go b/internal/intconv/i64_u64.go
new file mode 100644
index 00000000..c04da3cd
--- /dev/null
+++ b/internal/intconv/i64_u64.go
@@ -0,0 +1,10 @@
+package intconv
+
+// Int64ToUint64 converts v to uint64, returning an error if v is negative.
+func Int64ToUint64(v int64) (uint64, error) {
+	if v < 0 {
+		return 0, ErrOverflow
+	}
+
+	return uint64(v), nil
+}
diff --git a/internal/intconv/i_u32.go b/internal/intconv/i_u32.go
new file mode 100644
index 00000000..b3c602ef
--- /dev/null
+++ b/internal/intconv/i_u32.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// IntToUint32 converts v to uint32, returning an error if it overflows.
+func IntToUint32(v int) (uint32, error) {
+	if v < 0 || v > math.MaxUint32 {
+		return 0, ErrOverflow
+	}
+
+	return uint32(v), nil
+}
diff --git a/internal/intconv/i_u64.go b/internal/intconv/i_u64.go
new file mode 100644
index 00000000..cf57b677
--- /dev/null
+++ b/internal/intconv/i_u64.go
@@ -0,0 +1,10 @@
+package intconv
+
+// IntToUint64 converts v to uint64, returning an error if v is negative.
+func IntToUint64(v int) (uint64, error) {
+	if v < 0 {
+		return 0, ErrOverflow
+	}
+
+	return uint64(v), nil
+}
diff --git a/internal/intconv/se_u8_u32.go b/internal/intconv/se_u8_u32.go
new file mode 100644
index 00000000..bef34268
--- /dev/null
+++ b/internal/intconv/se_u8_u32.go
@@ -0,0 +1,10 @@
+package intconv
+
+// SignExtendByteToUint32 sign-extends b as a signed 8-bit integer into uint32.
+func SignExtendByteToUint32(b byte) uint32 {
+	if b&0x80 == 0 {
+		return uint32(b)
+	}
+
+	return 0xFFFFFF00 | uint32(b)
+}
diff --git a/internal/intconv/u32_i.go b/internal/intconv/u32_i.go
new file mode 100644
index 00000000..24147c8b
--- /dev/null
+++ b/internal/intconv/u32_i.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// Uint32ToInt converts v to int, returning an error if it overflows.
+func Uint32ToInt(v uint32) (int, error) {
+	if uint64(v) > uint64(math.MaxInt) {
+		return 0, ErrOverflow
+	}
+
+	return int(v), nil
+}
diff --git a/internal/intconv/u32_u8.go b/internal/intconv/u32_u8.go
new file mode 100644
index 00000000..40744051
--- /dev/null
+++ b/internal/intconv/u32_u8.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// Uint32ToUint8 converts v to uint8, returning an error if it overflows.
+func Uint32ToUint8(v uint32) (uint8, error) {
+	if v > math.MaxUint8 {
+		return 0, ErrOverflow
+	}
+
+	return uint8(v), nil
+}
diff --git a/internal/intconv/u64_i.go b/internal/intconv/u64_i.go
new file mode 100644
index 00000000..1e9acacd
--- /dev/null
+++ b/internal/intconv/u64_i.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// Uint64ToInt converts v to int, returning an error if it overflows.
+func Uint64ToInt(v uint64) (int, error) {
+	if v > uint64(math.MaxInt) {
+		return 0, ErrOverflow
+	}
+
+	return int(v), nil
+}
diff --git a/internal/intconv/u64_i64.go b/internal/intconv/u64_i64.go
new file mode 100644
index 00000000..2285142c
--- /dev/null
+++ b/internal/intconv/u64_i64.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// Uint64ToInt64 converts v to int64, returning an error if it overflows.
+func Uint64ToInt64(v uint64) (int64, error) {
+	if v > math.MaxInt64 {
+		return 0, ErrOverflow
+	}
+
+	return int64(v), nil
+}
diff --git a/internal/intconv/uptr_int.go b/internal/intconv/uptr_int.go
new file mode 100644
index 00000000..1ca4c674
--- /dev/null
+++ b/internal/intconv/uptr_int.go
@@ -0,0 +1,14 @@
+package intconv
+
+import (
+	"math"
+)
+
+// UintptrToInt converts v to int, returning an error if it overflows.
+func UintptrToInt(v uintptr) (int, error) {
+	if v > uintptr(math.MaxInt) {
+		return 0, ErrOverflow
+	}
+
+	return int(v), nil
+}