common: improve documentation comments (#16701)

This commit adds many comments and removes unused code.
It also removes the EmptyHash function, which had some uses
but was silly.

common/types.go

@@ -42,19 +42,30 @@ var (
 // Hash represents the 32 byte Keccak256 hash of arbitrary data.
 type Hash [HashLength]byte
 
+// BytesToHash sets b to hash.
+// If b is larger than len(h), b will be cropped from the left.
 func BytesToHash(b []byte) Hash {
 	var h Hash
 	h.SetBytes(b)
 	return h
 }
-func BigToHash(b *big.Int) Hash { return BytesToHash(b.Bytes()) }
-func HexToHash(s string) Hash   { return BytesToHash(FromHex(s)) }
 
-// Get the string representation of the underlying hash
-func (h Hash) Str() string   { return string(h[:]) }
+// BigToHash sets byte representation of b to hash.
+// If b is larger than len(h), b will be cropped from the left.
+func BigToHash(b *big.Int) Hash { return BytesToHash(b.Bytes()) }
+
+// HexToHash sets byte representation of s to hash.
+// If b is larger than len(h), b will be cropped from the left.
+func HexToHash(s string) Hash { return BytesToHash(FromHex(s)) }
+
+// Bytes gets the byte representation of the underlying hash.
 func (h Hash) Bytes() []byte { return h[:] }
+
+// Big converts a hash to a big integer.
 func (h Hash) Big() *big.Int { return new(big.Int).SetBytes(h[:]) }
-func (h Hash) Hex() string   { return hexutil.Encode(h[:]) }
+
+// Hex converts a hash to a hex string.
+func (h Hash) Hex() string { return hexutil.Encode(h[:]) }
 
 // TerminalString implements log.TerminalStringer, formatting a string for console
 // output during logging.
@@ -89,7 +100,8 @@ func (h Hash) MarshalText() ([]byte, error) {
 	return hexutil.Bytes(h[:]).MarshalText()
 }
 
-// Sets the hash to the value of b. If b is larger than len(h), 'b' will be cropped (from the left).
+// SetBytes sets the hash to the value of b.
+// If b is larger than len(h), b will be cropped from the left.
 func (h *Hash) SetBytes(b []byte) {
 	if len(b) > len(h) {
 		b = b[len(b)-HashLength:]
@@ -98,16 +110,6 @@ func (h *Hash) SetBytes(b []byte) {
 	copy(h[HashLength-len(b):], b)
 }
 
-// Set string `s` to h. If s is larger than len(h) s will be cropped (from left) to fit.
-func (h *Hash) SetString(s string) { h.SetBytes([]byte(s)) }
-
-// Sets h to other
-func (h *Hash) Set(other Hash) {
-	for i, v := range other {
-		h[i] = v
-	}
-}
-
 // Generate implements testing/quick.Generator.
 func (h Hash) Generate(rand *rand.Rand, size int) reflect.Value {
 	m := rand.Intn(len(h))
@@ -117,10 +119,6 @@ func (h Hash) Generate(rand *rand.Rand, size int) reflect.Value {
 	return reflect.ValueOf(h)
 }
 
-func EmptyHash(h Hash) bool {
-	return h == Hash{}
-}
-
 // UnprefixedHash allows marshaling a Hash without 0x prefix.
 type UnprefixedHash Hash
 
@@ -139,13 +137,21 @@ func (h UnprefixedHash) MarshalText() ([]byte, error) {
 // Address represents the 20 byte address of an Ethereum account.
 type Address [AddressLength]byte
 
+// BytesToAddress returns Address with value b.
+// If b is larger than len(h), b will be cropped from the left.
 func BytesToAddress(b []byte) Address {
 	var a Address
 	a.SetBytes(b)
 	return a
 }
+
+// BigToAddress returns Address with byte values of b.
+// If b is larger than len(h), b will be cropped from the left.
 func BigToAddress(b *big.Int) Address { return BytesToAddress(b.Bytes()) }
-func HexToAddress(s string) Address   { return BytesToAddress(FromHex(s)) }
+
+// HexToAddress returns Address with byte values of s.
+// If s is larger than len(h), s will be cropped from the left.
+func HexToAddress(s string) Address { return BytesToAddress(FromHex(s)) }
 
 // IsHexAddress verifies whether a string can represent a valid hex-encoded
 // Ethereum address or not.
@@ -156,11 +162,14 @@ func IsHexAddress(s string) bool {
 	return len(s) == 2*AddressLength && isHex(s)
 }
 
-// Get the string representation of the underlying address
-func (a Address) Str() string   { return string(a[:]) }
+// Bytes gets the string representation of the underlying address.
 func (a Address) Bytes() []byte { return a[:] }
+
+// Big converts an address to a big integer.
 func (a Address) Big() *big.Int { return new(big.Int).SetBytes(a[:]) }
-func (a Address) Hash() Hash    { return BytesToHash(a[:]) }
+
+// Hash converts an address to a hash by left-padding it with zeros.
+func (a Address) Hash() Hash { return BytesToHash(a[:]) }
 
 // Hex returns an EIP55-compliant hex string representation of the address.
 func (a Address) Hex() string {
@@ -184,7 +193,7 @@ func (a Address) Hex() string {
 	return "0x" + string(result)
 }
 
-// String implements the stringer interface and is used also by the logger.
+// String implements fmt.Stringer.
 func (a Address) String() string {
 	return a.Hex()
 }
@@ -195,7 +204,8 @@ func (a Address) Format(s fmt.State, c rune) {
 	fmt.Fprintf(s, "%"+string(c), a[:])
 }
 
-// Sets the address to the value of b. If b is larger than len(a) it will panic
+// SetBytes sets the address to the value of b.
+// If b is larger than len(a) it will panic.
 func (a *Address) SetBytes(b []byte) {
 	if len(b) > len(a) {
 		b = b[len(b)-AddressLength:]
@@ -203,16 +213,6 @@ func (a *Address) SetBytes(b []byte) {
 	copy(a[AddressLength-len(b):], b)
 }
 
-// Set string `s` to a. If s is larger than len(a) it will panic
-func (a *Address) SetString(s string) { a.SetBytes([]byte(s)) }
-
-// Sets a to other
-func (a *Address) Set(other Address) {
-	for i, v := range other {
-		a[i] = v
-	}
-}
-
 // MarshalText returns the hex representation of a.
 func (a Address) MarshalText() ([]byte, error) {
 	return hexutil.Bytes(a[:]).MarshalText()
@@ -228,7 +228,7 @@ func (a *Address) UnmarshalJSON(input []byte) error {
 	return hexutil.UnmarshalFixedJSON(addressT, input, a[:])
 }
 
-// UnprefixedHash allows marshaling an Address without 0x prefix.
+// UnprefixedAddress allows marshaling an Address without 0x prefix.
 type UnprefixedAddress Address
 
 // UnmarshalText decodes the address from hex. The 0x prefix is optional.