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Remove strict verifyContext invocation from hash_map implementation. (#22370)

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Fixes #19640

Co-authored-by: Andrew Kelley <andrew@ziglang.org>
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cdeler 2025-01-06 05:37:30 -08:00 committed by GitHub
parent 0bf44c3093
commit 745d3ed0ac
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1 changed files with 9 additions and 266 deletions
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lib/std/hash_map.zig
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@ -116,232 +116,6 @@ pub const StringIndexAdapter = struct {
pub const default_max_load_percentage = 80;
/// This function issues a compile error with a helpful message if there
/// is a problem with the provided context type. A context must have the following
/// member functions:
/// - hash(self, PseudoKey) Hash
/// - eql(self, PseudoKey, Key) bool
///
/// If you are passing a context to a *Adapted function, PseudoKey is the type
/// of the key parameter. Otherwise, when creating a HashMap or HashMapUnmanaged
/// type, PseudoKey = Key = K.
pub fn verifyContext(
comptime RawContext: type,
comptime PseudoKey: type,
comptime Key: type,
comptime Hash: type,
comptime is_array: bool,
) void {
comptime {
var allow_const_ptr = false;
var allow_mutable_ptr = false;
// Context is the actual namespace type. RawContext may be a pointer to Context.
var Context = RawContext;
// Make sure the context is a namespace type which may have member functions
switch (@typeInfo(Context)) {
.@"struct", .@"union", .@"enum" => {},
// Special-case .@"opaque" for a better error message
.@"opaque" => @compileError("Hash context must be a type with hash and eql member functions. Cannot use " ++ @typeName(Context) ++ " because it is opaque. Use a pointer instead."),
.pointer => |ptr| {
if (ptr.size != .One) {
@compileError("Hash context must be a type with hash and eql member functions. Cannot use " ++ @typeName(Context) ++ " because it is not a single pointer.");
}
Context = ptr.child;
allow_const_ptr = true;
allow_mutable_ptr = !ptr.is_const;
switch (@typeInfo(Context)) {
.@"struct", .@"union", .@"enum", .@"opaque" => {},
else => @compileError("Hash context must be a type with hash and eql member functions. Cannot use " ++ @typeName(Context)),
}
},
else => @compileError("Hash context must be a type with hash and eql member functions. Cannot use " ++ @typeName(Context)),
}
// Keep track of multiple errors so we can report them all.
var errors: []const u8 = "";
// Put common errors here, they will only be evaluated
// if the error is actually triggered.
const lazy = struct {
const prefix = "\n ";
const deep_prefix = prefix ++ " ";
const hash_signature = "fn (self, " ++ @typeName(PseudoKey) ++ ") " ++ @typeName(Hash);
const index_param = if (is_array) ", b_index: usize" else "";
const eql_signature = "fn (self, " ++ @typeName(PseudoKey) ++ ", " ++
@typeName(Key) ++ index_param ++ ") bool";
const err_invalid_hash_signature = prefix ++ @typeName(Context) ++ ".hash must be " ++ hash_signature ++
deep_prefix ++ "but is actually " ++ @typeName(@TypeOf(Context.hash));
const err_invalid_eql_signature = prefix ++ @typeName(Context) ++ ".eql must be " ++ eql_signature ++
deep_prefix ++ "but is actually " ++ @typeName(@TypeOf(Context.eql));
};
// Verify Context.hash(self, PseudoKey) => Hash
if (@hasDecl(Context, "hash")) {
const hash = Context.hash;
const info = @typeInfo(@TypeOf(hash));
if (info == .@"fn") {
const func = info.@"fn";
if (func.params.len != 2) {
errors = errors ++ lazy.err_invalid_hash_signature;
} else {
var emitted_signature = false;
if (func.params[0].type) |Self| {
if (Self == Context) {
// pass, this is always fine.
} else if (Self == *const Context) {
if (!allow_const_ptr) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_hash_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be a pointer because it is passed by value.";
}
} else if (Self == *Context) {
if (!allow_mutable_ptr) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_hash_signature;
emitted_signature = true;
}
if (!allow_const_ptr) {
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be a pointer because it is passed by value.";
} else {
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ " or " ++ @typeName(*const Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be non-const because it is passed by const pointer.";
}
}
} else {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_hash_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context);
if (allow_const_ptr) {
errors = errors ++ " or " ++ @typeName(*const Context);
if (allow_mutable_ptr) {
errors = errors ++ " or " ++ @typeName(*Context);
}
}
errors = errors ++ ", but is " ++ @typeName(Self);
}
}
if (func.params[1].type != null and func.params[1].type.? != PseudoKey) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_hash_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "Second parameter must be " ++ @typeName(PseudoKey) ++ ", but is " ++ @typeName(func.params[1].type.?);
}
if (func.return_type != null and func.return_type.? != Hash) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_hash_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "Return type must be " ++ @typeName(Hash) ++ ", but was " ++ @typeName(func.return_type.?);
}
// If any of these are generic (null), we cannot verify them.
// The call sites check the return type, but cannot check the
// parameters. This may cause compile errors with generic hash/eql functions.
}
} else {
errors = errors ++ lazy.err_invalid_hash_signature;
}
} else {
errors = errors ++ lazy.prefix ++ @typeName(Context) ++ " must declare a pub hash function with signature " ++ lazy.hash_signature;
}
// Verify Context.eql(self, PseudoKey, Key) => bool
if (@hasDecl(Context, "eql")) {
const eql = Context.eql;
const info = @typeInfo(@TypeOf(eql));
if (info == .@"fn") {
const func = info.@"fn";
const args_len = if (is_array) 4 else 3;
if (func.params.len != args_len) {
errors = errors ++ lazy.err_invalid_eql_signature;
} else {
var emitted_signature = false;
if (func.params[0].type) |Self| {
if (Self == Context) {
// pass, this is always fine.
} else if (Self == *const Context) {
if (!allow_const_ptr) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be a pointer because it is passed by value.";
}
} else if (Self == *Context) {
if (!allow_mutable_ptr) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
if (!allow_const_ptr) {
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be a pointer because it is passed by value.";
} else {
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context) ++ " or " ++ @typeName(*const Context) ++ ", but is " ++ @typeName(Self);
errors = errors ++ lazy.deep_prefix ++ "Note: Cannot be non-const because it is passed by const pointer.";
}
}
} else {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "First parameter must be " ++ @typeName(Context);
if (allow_const_ptr) {
errors = errors ++ " or " ++ @typeName(*const Context);
if (allow_mutable_ptr) {
errors = errors ++ " or " ++ @typeName(*Context);
}
}
errors = errors ++ ", but is " ++ @typeName(Self);
}
}
if (func.params[1].type.? != PseudoKey) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "Second parameter must be " ++ @typeName(PseudoKey) ++ ", but is " ++ @typeName(func.params[1].type.?);
}
if (func.params[2].type.? != Key) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "Third parameter must be " ++ @typeName(Key) ++ ", but is " ++ @typeName(func.params[2].type.?);
}
if (func.return_type.? != bool) {
if (!emitted_signature) {
errors = errors ++ lazy.err_invalid_eql_signature;
emitted_signature = true;
}
errors = errors ++ lazy.deep_prefix ++ "Return type must be bool, but was " ++ @typeName(func.return_type.?);
}
// If any of these are generic (null), we cannot verify them.
// The call sites check the return type, but cannot check the
// parameters. This may cause compile errors with generic hash/eql functions.
}
} else {
errors = errors ++ lazy.err_invalid_eql_signature;
}
} else {
errors = errors ++ lazy.prefix ++ @typeName(Context) ++ " must declare a pub eql function with signature " ++ lazy.eql_signature;
}
if (errors.len != 0) {
// errors begins with a newline (from lazy.prefix)
@compileError("Problems found with hash context type " ++ @typeName(Context) ++ ":" ++ errors);
}
}
}
/// General purpose hash table.
/// No order is guaranteed and any modification invalidates live iterators.
/// It provides fast operations (lookup, insertion, deletion) with quite high
@ -368,10 +142,6 @@ pub fn HashMap(
allocator: Allocator,
ctx: Context,
comptime {
verifyContext(Context, K, K, u64, false);
}
/// The type of the unmanaged hash map underlying this wrapper
pub const Unmanaged = HashMapUnmanaged(K, V, Context, max_load_percentage);
/// An entry, containing pointers to a key and value stored in the map
@ -734,10 +504,6 @@ pub fn HashMapUnmanaged(
return struct {
const Self = @This();
comptime {
verifyContext(Context, K, K, u64, false);
}
// This is actually a midway pointer to the single buffer containing
// a `Header` field, the `Metadata`s and `Entry`s.
// At `-@sizeOf(Header)` is the Header field.
@ -1097,7 +863,7 @@ pub fn HashMapUnmanaged(
pub fn putAssumeCapacityNoClobberContext(self: *Self, key: K, value: V, ctx: Context) void {
assert(!self.containsContext(key, ctx));
const hash = ctx.hash(key);
const hash: Hash = ctx.hash(key);
const mask = self.capacity() - 1;
var idx: usize = @truncate(hash & mask);
@ -1188,8 +954,6 @@ pub fn HashMapUnmanaged(
/// Find the index containing the data for the given key.
fn getIndex(self: Self, key: anytype, ctx: anytype) ?usize {
comptime verifyContext(@TypeOf(ctx), @TypeOf(key), K, Hash, false);
if (self.size == 0) {
// We use cold instead of unlikely to force a jump to this case,
// no matter the weight of the opposing side.
@ -1199,12 +963,8 @@ pub fn HashMapUnmanaged(
// If you get a compile error on this line, it means that your generic hash
// function is invalid for these parameters.
const hash = ctx.hash(key);
// verifyContext can't verify the return type of generic hash functions,
// so we need to double-check it here.
if (@TypeOf(hash) != Hash) {
@compileError("Context " ++ @typeName(@TypeOf(ctx)) ++ " has a generic hash function that returns the wrong type! " ++ @typeName(Hash) ++ " was expected, but found " ++ @typeName(@TypeOf(hash)));
}
const hash: Hash = ctx.hash(key);
const mask = self.capacity() - 1;
const fingerprint = Metadata.takeFingerprint(hash);
// Don't loop indefinitely when there are no empty slots.
@ -1215,15 +975,8 @@ pub fn HashMapUnmanaged(
while (!metadata[0].isFree() and limit != 0) {
if (metadata[0].isUsed() and metadata[0].fingerprint == fingerprint) {
const test_key = &self.keys()[idx];
// If you get a compile error on this line, it means that your generic eql
// function is invalid for these parameters.
const eql = ctx.eql(key, test_key.*);
// verifyContext can't verify the return type of generic eql functions,
// so we need to double-check it here.
if (@TypeOf(eql) != bool) {
@compileError("Context " ++ @typeName(@TypeOf(ctx)) ++ " has a generic eql function that returns the wrong type! bool was expected, but found " ++ @typeName(@TypeOf(eql)));
}
if (eql) {
if (ctx.eql(key, test_key.*)) {
return idx;
}
}
@ -1378,16 +1131,11 @@ pub fn HashMapUnmanaged(
return result;
}
pub fn getOrPutAssumeCapacityAdapted(self: *Self, key: anytype, ctx: anytype) GetOrPutResult {
comptime verifyContext(@TypeOf(ctx), @TypeOf(key), K, Hash, false);
// If you get a compile error on this line, it means that your generic hash
// function is invalid for these parameters.
const hash = ctx.hash(key);
// verifyContext can't verify the return type of generic hash functions,
// so we need to double-check it here.
if (@TypeOf(hash) != Hash) {
@compileError("Context " ++ @typeName(@TypeOf(ctx)) ++ " has a generic hash function that returns the wrong type! " ++ @typeName(Hash) ++ " was expected, but found " ++ @typeName(@TypeOf(hash)));
}
const hash: Hash = ctx.hash(key);
const mask = self.capacity() - 1;
const fingerprint = Metadata.takeFingerprint(hash);
var limit = self.capacity();
@ -1400,13 +1148,8 @@ pub fn HashMapUnmanaged(
const test_key = &self.keys()[idx];
// If you get a compile error on this line, it means that your generic eql
// function is invalid for these parameters.
const eql = ctx.eql(key, test_key.*);
// verifyContext can't verify the return type of generic eql functions,
// so we need to double-check it here.
if (@TypeOf(eql) != bool) {
@compileError("Context " ++ @typeName(@TypeOf(ctx)) ++ " has a generic eql function that returns the wrong type! bool was expected, but found " ++ @typeName(@TypeOf(eql)));
}
if (eql) {
if (ctx.eql(key, test_key.*)) {
return GetOrPutResult{
.key_ptr = test_key,
.value_ptr = &self.values()[idx],