zeek/src/Type.h

// See the file "COPYING" in the main distribution directory for copyright.

#pragma once

#include <list>
#include <map>
#include <optional>
#include <set>
#include <string>
#include <unordered_map>

#include "zeek/Attr.h"
#include "zeek/ID.h"
#include "zeek/IntrusivePtr.h"
#include "zeek/Obj.h"
#include "zeek/ZeekList.h"

namespace zeek
	{

class Val;
union ZVal;
class EnumVal;
class TableVal;
using ValPtr = IntrusivePtr<Val>;
using EnumValPtr = IntrusivePtr<EnumVal>;
using TableValPtr = IntrusivePtr<TableVal>;

namespace detail
	{

class Expr;
class ListExpr;
class Attributes;
using ListExprPtr = IntrusivePtr<ListExpr>;

	} // namespace detail

// Zeek types.
enum TypeTag
	{
	TYPE_VOID, // 0
	TYPE_BOOL, // 1
	TYPE_INT, // 2
	TYPE_COUNT, // 3
	TYPE_DOUBLE, // 4
	TYPE_TIME, // 5
	TYPE_INTERVAL, // 6
	TYPE_STRING, // 7
	TYPE_PATTERN, // 8
	TYPE_ENUM, // 9
	TYPE_TIMER, // 10
	TYPE_PORT, // 11
	TYPE_ADDR, // 12
	TYPE_SUBNET, // 13
	TYPE_ANY, // 14
	TYPE_TABLE, // 15
	TYPE_UNION, // 16
	TYPE_RECORD, // 17
	TYPE_LIST, // 18
	TYPE_FUNC, // 19
	TYPE_FILE, // 20
	TYPE_VECTOR, // 21
	TYPE_OPAQUE, // 22
	TYPE_TYPE, // 23
	TYPE_ERROR // 24
#define NUM_TYPES (int(TYPE_ERROR) + 1)
	};

// Returns the name of the type.
extern const char* type_name(TypeTag t);

constexpr bool is_network_order(TypeTag tag) noexcept
	{
	return tag == TYPE_PORT;
	}

enum FunctionFlavor
	{
	FUNC_FLAVOR_FUNCTION,
	FUNC_FLAVOR_EVENT,
	FUNC_FLAVOR_HOOK
	};

enum InternalTypeTag : uint16_t
	{
	TYPE_INTERNAL_VOID,
	TYPE_INTERNAL_INT,
	TYPE_INTERNAL_UNSIGNED,
	TYPE_INTERNAL_DOUBLE,
	TYPE_INTERNAL_STRING,
	TYPE_INTERNAL_ADDR,
	TYPE_INTERNAL_SUBNET,
	TYPE_INTERNAL_OTHER,
	TYPE_INTERNAL_ERROR
	};

constexpr InternalTypeTag to_internal_type_tag(TypeTag tag) noexcept
	{
	switch ( tag )
		{
		case TYPE_VOID:
			return TYPE_INTERNAL_VOID;

		case TYPE_BOOL:
		case TYPE_INT:
		case TYPE_ENUM:
			return TYPE_INTERNAL_INT;

		case TYPE_COUNT:
		case TYPE_PORT:
			return TYPE_INTERNAL_UNSIGNED;

		case TYPE_DOUBLE:
		case TYPE_TIME:
		case TYPE_INTERVAL:
			return TYPE_INTERNAL_DOUBLE;

		case TYPE_STRING:
			return TYPE_INTERNAL_STRING;

		case TYPE_ADDR:
			return TYPE_INTERNAL_ADDR;

		case TYPE_SUBNET:
			return TYPE_INTERNAL_SUBNET;

		case TYPE_PATTERN:
		case TYPE_TIMER:
		case TYPE_ANY:
		case TYPE_TABLE:
		case TYPE_UNION:
		case TYPE_RECORD:
		case TYPE_LIST:
		case TYPE_FUNC:
		case TYPE_FILE:
		case TYPE_OPAQUE:
		case TYPE_VECTOR:
		case TYPE_TYPE:
			return TYPE_INTERNAL_OTHER;

		case TYPE_ERROR:
			return TYPE_INTERNAL_ERROR;
		}

	/* this should be unreachable */
	return TYPE_INTERNAL_VOID;
	}

class Type;
class TypeList;
class TableType;
class SetType;
class RecordType;
class SubNetType;
class FuncType;
class EnumType;
class VectorType;
class TypeType;
class OpaqueType;
class FileType;

using TypePtr = IntrusivePtr<Type>;
using TypeListPtr = IntrusivePtr<TypeList>;
using TableTypePtr = IntrusivePtr<TableType>;
using SetTypePtr = IntrusivePtr<SetType>;
using RecordTypePtr = IntrusivePtr<RecordType>;
using SubNetTypePtr = IntrusivePtr<SubNetType>;
using FuncTypePtr = IntrusivePtr<FuncType>;
using EnumTypePtr = IntrusivePtr<EnumType>;
using VectorTypePtr = IntrusivePtr<VectorType>;
using TypeTypePtr = IntrusivePtr<TypeType>;
using OpaqueTypePtr = IntrusivePtr<OpaqueType>;
using FileTypePtr = IntrusivePtr<FileType>;

constexpr int DOES_NOT_MATCH_INDEX = 0;
constexpr int MATCHES_INDEX_SCALAR = 1;
constexpr int MATCHES_INDEX_VECTOR = 2;

class Type : public Obj
	{
public:
	static inline const TypePtr nil;

	explicit Type(TypeTag tag, bool base_type = false);

	// Performs a shallow clone operation of the Zeek type.
	// This especially means that especially for tables the types
	// are not recursively cloned; altering one type will in this case
	// alter one of them.
	// The main use for this is alias tracking.
	// Clone operations will mostly be implemented in the derived classes;
	// in addition cloning will be limited to classes that can be reached by
	// the script-level.
	virtual TypePtr ShallowClone();

	TypeTag Tag() const { return tag; }
	InternalTypeTag InternalType() const { return internal_tag; }

	// Whether it's stored in network order.
	bool IsNetworkOrder() const { return is_network_order; }

	// Type-checks the given expression list, returning
	// MATCHES_INDEX_SCALAR = 1 if it matches this type's index
	// and produces a scalar result (and promoting its
	// subexpressions as necessary); MATCHES_INDEX_VECTOR = 2
	// if it matches and produces a vector result; and
	// DOES_NOT_MATCH_INDEX = 0 if it can't match (or the type
	// is not an indexable type).
	virtual int MatchesIndex(detail::ListExpr* index) const;

	// Returns the type yielded by this type.  For example, if
	// this type is a table[string] of port, then returns the "port"
	// type.  Returns nil if this is not an index type.
	virtual const TypePtr& Yield() const;

	const TypeList* AsTypeList() const;
	TypeList* AsTypeList();

	const TableType* AsTableType() const;
	TableType* AsTableType();

	const SetType* AsSetType() const;
	SetType* AsSetType();

	const RecordType* AsRecordType() const;
	RecordType* AsRecordType();

	const SubNetType* AsSubNetType() const;
	SubNetType* AsSubNetType();

	const FuncType* AsFuncType() const;
	FuncType* AsFuncType();

	const FileType* AsFileType() const;
	FileType* AsFileType();

	const EnumType* AsEnumType() const;
	EnumType* AsEnumType();

	const VectorType* AsVectorType() const;
	VectorType* AsVectorType();

	const OpaqueType* AsOpaqueType() const;
	OpaqueType* AsOpaqueType();

	const TypeType* AsTypeType() const;
	TypeType* AsTypeType();

	bool IsSet() const { return tag == TYPE_TABLE && ! Yield(); }

	bool IsTable() const { return tag == TYPE_TABLE && Yield(); }

	Type* Ref()
		{
		::zeek::Ref(this);
		return this;
		}

	void Describe(ODesc* d) const override;
	virtual void DescribeReST(ODesc* d, bool roles_only = false) const;

	[[deprecated("Remove in v5.1. MemoryAllocation() is deprecated and will be removed. See "
	             "GHI-572.")]] virtual unsigned
	MemoryAllocation() const;

	void SetName(const std::string& arg_name) { name = arg_name; }
	const std::string& GetName() const { return name; }

	struct TypePtrComparer
		{
		bool operator()(const TypePtr& a, const TypePtr& b) const { return a.get() < b.get(); }
		};
	using TypePtrSet = std::set<TypePtr, TypePtrComparer>;
	using TypeAliasMap = std::map<std::string, TypePtrSet, std::less<>>;

	/**
	 * Returns a mapping of type-name to all other type names declared as
	 * an alias to it.
	 */
	static const TypeAliasMap& GetAliasMap() { return type_aliases; }

	/**
	 * Returns true if the given type name has any declared aliases
	 */
	static bool HasAliases(std::string_view type_name)
		{
		return Type::type_aliases.find(type_name) != Type::type_aliases.end();
		}

	/**
	 * Returns the set of all type names declared as an aliases to the given
	 * type name.  A static empty set is returned if there are no aliases.
	 */
	static const TypePtrSet& Aliases(std::string_view type_name)
		{
		static TypePtrSet empty;
		auto it = Type::type_aliases.find(type_name);
		return it == Type::type_aliases.end() ? empty : it->second;
		}

	/**
	 * Registers a new type alias.
	 * @param type_name  the name of the type to register a new alias for.
	 * @param type  the associated alias type of *type_name*.
	 * @return  true if the alias is now registered or false if the alias was
	 * already previously registered.
	 */
	static bool RegisterAlias(std::string_view type_name, TypePtr type)
		{
		auto it = Type::type_aliases.find(type_name);
		if ( it == Type::type_aliases.end() )
			it = Type::type_aliases.emplace(std::string{type_name}, TypePtrSet{}).first;
		return it->second.emplace(std::move(type)).second;
		}

protected:
	Type() = default;

	void SetError();

private:
	TypeTag tag;
	InternalTypeTag internal_tag;
	bool is_network_order;
	bool base_type;
	std::string name;

	static TypeAliasMap type_aliases;
	};

class TypeList final : public Type
	{
public:
	explicit TypeList(TypePtr arg_pure_type = nullptr)
		: Type(TYPE_LIST), pure_type(std::move(arg_pure_type))
		{
		}

	~TypeList() override = default;

	const std::vector<TypePtr>& GetTypes() const { return types; }

	bool IsPure() const { return pure_type != nullptr; }

	// Returns the underlying pure type, or nil if the list
	// is not pure or is empty.
	const TypePtr& GetPureType() const { return pure_type; }

	// True if all of the types match t, false otherwise.  If
	// is_init is true, then the matching is done in the context
	// of an initialization.
	bool AllMatch(const Type* t, bool is_init) const;
	bool AllMatch(const TypePtr& t, bool is_init) const { return AllMatch(t.get(), is_init); }

	void Append(TypePtr t);
	void AppendEvenIfNotPure(TypePtr t);

	void Describe(ODesc* d) const override;

	[[deprecated("Remove in v5.1. MemoryAllocation() is deprecated and will be removed. See "
	             "GHI-572.")]] unsigned int
	MemoryAllocation() const override;

protected:
	TypePtr pure_type;
	std::vector<TypePtr> types;
	};

class IndexType : public Type
	{
public:
	int MatchesIndex(detail::ListExpr* index) const override;

	const TypeListPtr& GetIndices() const { return indices; }

	const std::vector<TypePtr>& GetIndexTypes() const { return indices->GetTypes(); }

	const TypePtr& Yield() const override { return yield_type; }

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;

	// Returns true if this table is solely indexed by subnet.
	bool IsSubNetIndex() const;

protected:
	IndexType(TypeTag t, TypeListPtr arg_indices, TypePtr arg_yield_type)
		: Type(t), indices(std::move(arg_indices)), yield_type(std::move(arg_yield_type))
		{
		}

	~IndexType() override = default;

	TypeListPtr indices;
	TypePtr yield_type;
	};

class TableType : public IndexType
	{
public:
	TableType(TypeListPtr ind, TypePtr yield);

	/**
	 * Assesses whether an &expire_func attribute's function type is compatible
	 * with this table type.
	 * @param attr  the &expire_func attribute to check (this method must not be
	 * called with other type of attributes).
	 * @return  true if compatible, false if not
	 */
	bool CheckExpireFuncCompatibility(const detail::AttrPtr& attr);

	TypePtr ShallowClone() override;

	// Returns true if this table type is "unspecified", which is
	// what one gets using an empty "set()" or "table()" constructor.
	bool IsUnspecifiedTable() const;
	};

class SetType final : public TableType
	{
public:
	SetType(TypeListPtr ind, detail::ListExprPtr arg_elements);
	~SetType() override;

	TypePtr ShallowClone() override;

	const detail::ListExprPtr& Elements() const { return elements; }

protected:
	detail::ListExprPtr elements;
	};

class FuncType final : public Type
	{
public:
	static inline const FuncTypePtr nil;

	/**
	 * Prototype is only currently used for events and hooks which declare
	 * multiple signature prototypes that allow users to have handlers
	 * with various argument permutations.
	 */
	struct Prototype
		{
		bool deprecated;
		std::string deprecation_msg;
		RecordTypePtr args;
		// Maps from parameter index in canonical prototype to
		// parameter index in this alternate prorotype.
		std::map<int, int> offsets;
		};

	FuncType(RecordTypePtr args, TypePtr yield, FunctionFlavor f);

	TypePtr ShallowClone() override;

	const RecordTypePtr& Params() const { return args; }

	const TypePtr& Yield() const override { return yield; }

	void SetYieldType(TypePtr arg_yield) { yield = std::move(arg_yield); }
	FunctionFlavor Flavor() const { return flavor; }
	std::string FlavorString() const;

	// Used to convert a function type to an event or hook type.
	void ClearYieldType(FunctionFlavor arg_flav)
		{
		yield = nullptr;
		flavor = arg_flav;
		}

	int MatchesIndex(detail::ListExpr* index) const override;
	bool CheckArgs(const TypePList* args, bool is_init = false, bool do_warn = true) const;
	bool CheckArgs(const std::vector<TypePtr>& args, bool is_init = false,
	               bool do_warn = true) const;

	const TypeListPtr& ParamList() const { return arg_types; }

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;

	/**
	 * Adds a new event/hook signature allowed for use in handlers.
	 */
	void AddPrototype(Prototype s);

	/**
	 * Returns a prototype signature that matches the desired argument types.
	 */
	std::optional<Prototype> FindPrototype(const RecordType& args) const;

	/**
	 * Returns all allowed function prototypes.
	 */
	const std::vector<Prototype>& Prototypes() const { return prototypes; }

	/**
	 * A single lambda "capture" (outer variable used in a lambda's body).
	 */
	struct Capture
		{
		detail::IDPtr id;
		bool deep_copy;
		};

	using CaptureList = std::vector<Capture>;

	/**
	 * Sets this function's set of captures.  Only valid for lambdas.
	 *
	 * @param captures  if non-nil, a list of the lambda's captures
	 */
	void SetCaptures(std::optional<CaptureList> captures);

	/**
	 * Returns the captures declared for this function, or nil if none.
	 *
	 * @return a vector giving the captures
	 */
	const std::optional<CaptureList>& GetCaptures() const { return captures; }

protected:
	friend FuncTypePtr make_intrusive<FuncType>();

	FuncType() : Type(TYPE_FUNC) { flavor = FUNC_FLAVOR_FUNCTION; }
	RecordTypePtr args;
	TypeListPtr arg_types;
	TypePtr yield;
	FunctionFlavor flavor;
	std::vector<Prototype> prototypes;

	std::optional<CaptureList> captures; // if nil then no captures specified
	};

class TypeType final : public Type
	{
public:
	explicit TypeType(TypePtr t) : zeek::Type(TYPE_TYPE), type(std::move(t)) { }
	TypePtr ShallowClone() override { return make_intrusive<TypeType>(type); }

	const TypePtr& GetType() const { return type; }

	template <class T> IntrusivePtr<T> GetType() const { return cast_intrusive<T>(type); }

protected:
	TypePtr type;
	};

class TypeDecl final
	{
public:
	TypeDecl() = default;
	TypeDecl(const char* i, TypePtr t, detail::AttributesPtr attrs = nullptr);
	TypeDecl(const TypeDecl& other);
	~TypeDecl();

	const detail::AttrPtr& GetAttr(detail::AttrTag a) const
		{
		return attrs ? attrs->Find(a) : detail::Attr::nil;
		}

	void DescribeReST(ODesc* d, bool roles_only = false) const;

	TypePtr type;
	detail::AttributesPtr attrs;
	const char* id = nullptr;
	};

using type_decl_list = PList<TypeDecl>;

// The following tracks how to initialize a given field.  We don't define
// it here because it requires pulling in a bunch of low-level headers that
// would be nice to avoid.
class FieldInit;

class RecordType final : public Type
	{
public:
	explicit RecordType(type_decl_list* types);
	TypePtr ShallowClone() override;

	~RecordType() override;

	bool HasField(const char* field) const;

	/**
	 * Looks up a field by name and returns its type.  No check for invalid
	 * field name is performed.
	 */
	const TypePtr& GetFieldType(const char* field_name) const
		{
		return GetFieldType(FieldOffset(field_name));
		}

	/**
	 * Looks up a field by name and returns its type as cast to @c T.
	 * No check for invalid field name is performed.
	 */
	template <class T> IntrusivePtr<T> GetFieldType(const char* field_name) const
		{
		return cast_intrusive<T>(GetFieldType(field_name));
		}

	/**
	 * Looks up a field by its index and returns its type.  No check for
	 * invalid field offset is performed.
	 */
	const TypePtr& GetFieldType(int field_index) const { return (*types)[field_index]->type; }

	/**
	 * Looks up a field by its index and returns its type as cast to @c T.
	 * No check for invalid field offset is performed.
	 */
	template <class T> IntrusivePtr<T> GetFieldType(int field_index) const
		{
		return cast_intrusive<T>((*types)[field_index]->type);
		}

	ValPtr FieldDefault(int field) const;

	// A field's offset is its position in the type_decl_list,
	// starting at 0.  Returns negative if the field doesn't exist.
	int FieldOffset(const char* field) const;

	// Given an offset, returns the field's name.
	const char* FieldName(int field) const;

	const type_decl_list* Types() const { return types; }
	type_decl_list* Types() { return types; }

	// Given an offset, returns the field's TypeDecl.
	const TypeDecl* FieldDecl(int field) const;
	TypeDecl* FieldDecl(int field);

	// Returns flags corresponding to which fields in the record
	// have types requiring memory management (reference counting).
	const std::vector<bool>& ManagedFields() const { return managed_fields; }

	int NumFields() const { return num_fields; }
	int NumOrigFields() const { return num_orig_fields; }

	/**
	 * Returns a "record_field_table" value for introspection purposes.
	 * @param rv  an optional record value, if given the values of
	 * all fields will be provided in the returned table.
	 */
	TableValPtr GetRecordFieldsVal(const RecordVal* rv = nullptr) const;

	// Returns null if all is ok, otherwise a pointer to an error message.
	const char* AddFields(const type_decl_list& types, bool add_log_attr = false);

	void AddFieldsDirectly(const type_decl_list& types, bool add_log_attr = false);

	/**
	 *
	 * Populates a new instance of the record with its initial values.
	 * @param r  The record's underlying value vector.
	 */
	void Create(std::vector<std::optional<ZVal>>& r) const;

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;
	void DescribeFields(ODesc* d) const;
	void DescribeFieldsReST(ODesc* d, bool func_args) const;

	bool IsFieldDeprecated(int field) const
		{
		const TypeDecl* decl = FieldDecl(field);
		return decl && decl->GetAttr(detail::ATTR_DEPRECATED) != nullptr;
		}

	bool FieldHasAttr(int field, detail::AttrTag at) const
		{
		const TypeDecl* decl = FieldDecl(field);
		return decl && decl->GetAttr(at) != nullptr;
		}

	std::string GetFieldDeprecationWarning(int field, bool has_check) const;

protected:
	RecordType() { types = nullptr; }

	void AddField(unsigned int field, const TypeDecl* td);

	// Maps each field to how to initialize it.  Uses pointers due to
	// keeping the FieldInit definition private to Type.cc (see above).
	std::vector<FieldInit*> field_inits;

	// If we were willing to bound the size of records, then we could
	// use std::bitset here instead.
	std::vector<bool> managed_fields;

	// Number of fields in the type.
	int num_fields;

	// Number of fields in the type when originally declared.
	int num_orig_fields;

	type_decl_list* types;
	};

class SubNetType final : public Type
	{
public:
	SubNetType();
	void Describe(ODesc* d) const override;
	};

class FileType final : public Type
	{
public:
	explicit FileType(TypePtr yield_type);
	TypePtr ShallowClone() override { return make_intrusive<FileType>(yield); }
	~FileType() override;

	const TypePtr& Yield() const override { return yield; }

	void Describe(ODesc* d) const override;

protected:
	TypePtr yield;
	};

class OpaqueType final : public Type
	{
public:
	explicit OpaqueType(const std::string& name);
	TypePtr ShallowClone() override { return make_intrusive<OpaqueType>(name); }
	~OpaqueType() override{};

	const std::string& Name() const { return name; }

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;

protected:
	OpaqueType() { }

	std::string name;
	};

class EnumType final : public Type
	{
public:
	typedef std::list<std::pair<std::string, bro_int_t>> enum_name_list;

	explicit EnumType(const EnumType* e);
	explicit EnumType(const std::string& arg_name);
	TypePtr ShallowClone() override;
	~EnumType() override;

	// The value of this name is next internal counter value, starting
	// with zero. The internal counter is incremented.
	void AddName(const std::string& module_name, const char* name, bool is_export,
	             detail::Expr* deprecation = nullptr, bool from_redef = false);

	// The value of this name is set to val. Once a value has been
	// explicitly assigned using this method, no further names can be
	// added that aren't likewise explicitly initalized.
	void AddName(const std::string& module_name, const char* name, bro_int_t val, bool is_export,
	             detail::Expr* deprecation = nullptr, bool from_redef = false);

	// -1 indicates not found.  Second version is for full names
	// that already incorporate the module.
	bro_int_t Lookup(const std::string& module_name, const char* name) const;
	bro_int_t Lookup(const std::string& full_name) const;

	const char* Lookup(bro_int_t value) const; // Returns 0 if not found

	// Returns the list of defined names with their values. The names
	// will be fully qualified with their module name.
	enum_name_list Names() const;

	bool HasRedefs() const { return has_redefs; }

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;

	const EnumValPtr& GetEnumVal(bro_int_t i);

	// Only for use by C++-generated code.  Non-protected because we
	// don't know in advance the names of the functions that will
	// access it.
	void AddNameInternal(const std::string& full_name, bro_int_t val);

protected:
	void AddNameInternal(const std::string& module_name, const char* name, bro_int_t val,
	                     bool is_export);

	void CheckAndAddName(const std::string& module_name, const char* name, bro_int_t val,
	                     bool is_export, detail::Expr* deprecation = nullptr,
	                     bool from_redef = false);

	typedef std::map<std::string, bro_int_t> NameMap;
	NameMap names;

	// Whether any of the elements of the enum were added via redef's.
	bool has_redefs = false;

	using ValMap = std::unordered_map<bro_int_t, EnumValPtr>;
	ValMap vals;

	// The counter is initialized to 0 and incremented on every implicit
	// auto-increment name that gets added (thus its > 0 if
	// auto-increment is used).  Once an explicit value has been
	// specified, the counter is set to -1. This way counter can be used
	// as a flag to prevent mixing of auto-increment and explicit
	// enumerator specifications.
	bro_int_t counter;
	};

class VectorType final : public Type
	{
public:
	explicit VectorType(TypePtr t);
	TypePtr ShallowClone() override;
	~VectorType() override;

	const TypePtr& Yield() const override;

	int MatchesIndex(detail::ListExpr* index) const override;

	// Returns true if this table type is "unspecified", which is what one
	// gets using an empty "vector()" constructor.
	bool IsUnspecifiedVector() const;

	void Describe(ODesc* d) const override;
	void DescribeReST(ODesc* d, bool roles_only = false) const override;

protected:
	TypePtr yield_type;
	};

// True if the two types are equivalent.  If is_init is true then the test is
// done in the context of an initialization. If match_record_field_names is
// true then for record types the field names have to match, too.
extern bool same_type(const Type& t1, const Type& t2, bool is_init = false,
                      bool match_record_field_names = true);
inline bool same_type(const TypePtr& t1, const TypePtr& t2, bool is_init = false,
                      bool match_record_field_names = true)
	{
	return same_type(*t1, *t2, is_init, match_record_field_names);
	}
inline bool same_type(const Type* t1, const Type* t2, bool is_init = false,
                      bool match_record_field_names = true)
	{
	return same_type(*t1, *t2, is_init, match_record_field_names);
	}
inline bool same_type(const TypePtr& t1, const Type* t2, bool is_init = false,
                      bool match_record_field_names = true)
	{
	return same_type(*t1, *t2, is_init, match_record_field_names);
	}
inline bool same_type(const Type* t1, const TypePtr& t2, bool is_init = false,
                      bool match_record_field_names = true)
	{
	return same_type(*t1, *t2, is_init, match_record_field_names);
	}

// True if the two attribute lists are equivalent.
extern bool same_attrs(const detail::Attributes* a1, const detail::Attributes* a2);

// Returns true if the record sub_rec can be promoted to the record
// super_rec.
extern bool record_promotion_compatible(const RecordType* super_rec, const RecordType* sub_rec);

// If the given Type is a TypeList with just one element, returns
// that element, otherwise returns the type.
extern const Type* flatten_type(const Type* t);
extern Type* flatten_type(Type* t);

// Returns the "maximum" of two type tags, in a type-promotion sense.
extern TypeTag max_type(TypeTag t1, TypeTag t2);

// Given two types, returns the "merge", in which promotable types
// are promoted to the maximum of the two.  Returns nil (and generates
// an error message) if the types are incompatible.
TypePtr merge_types(const TypePtr& t1, const TypePtr& t2);

// Given a list of expressions, returns a (ref'd) type reflecting
// a merged type consistent across all of them, or nil if this
// cannot be done.
TypePtr merge_type_list(detail::ListExpr* elements);

// Given an expression, infer its type when used for an initialization.
TypePtr init_type(detail::Expr* init);

// Returns true if argument is an atomic type.
bool is_atomic_type(const Type& t);
inline bool is_atomic_type(const Type* t)
	{
	return is_atomic_type(*t);
	}
inline bool is_atomic_type(const TypePtr& t)
	{
	return is_atomic_type(*t);
	}

// True if the given type tag corresponds to type that can be assigned to.
extern bool is_assignable(TypeTag t);
inline bool is_assignable(Type* t)
	{
	return is_assignable(t->Tag());
	}

// True if the given type tag corresponds to an integral type.
inline bool IsIntegral(TypeTag t)
	{
	return (t == TYPE_INT || t == TYPE_COUNT);
	}

// True if the given type tag corresponds to an arithmetic type.
inline bool IsArithmetic(TypeTag t)
	{
	return (IsIntegral(t) || t == TYPE_DOUBLE);
	}

// True if the given type tag corresponds to a boolean type.
inline bool IsBool(TypeTag t)
	{
	return (t == TYPE_BOOL);
	}

// True if the given type tag corresponds to an interval type.
inline bool IsInterval(TypeTag t)
	{
	return (t == TYPE_INTERVAL);
	}

// True if the given type tag corresponds to a record type.
inline bool IsRecord(TypeTag t)
	{
	return (t == TYPE_RECORD || t == TYPE_UNION);
	}

// True if the given type tag corresponds to a function type.
inline bool IsFunc(TypeTag t)
	{
	return (t == TYPE_FUNC);
	}

// True if the given type type is a vector.
inline bool IsVector(TypeTag t)
	{
	return (t == TYPE_VECTOR);
	}

// True if the given type type is a string.
inline bool IsString(TypeTag t)
	{
	return (t == TYPE_STRING);
	}

// True if the given type is a container aggregate.
inline bool IsAggr(TypeTag tag)
	{
	return tag == TYPE_VECTOR || tag == TYPE_TABLE || tag == TYPE_RECORD;
	}
inline bool IsAggr(const Type* t)
	{
	return IsAggr(t->Tag());
	}
inline bool IsAggr(const TypePtr& t)
	{
	return IsAggr(t->Tag());
	}

// True if the given type tag corresponds to the error type.
inline bool IsErrorType(TypeTag t)
	{
	return (t == TYPE_ERROR);
	}

// True if both tags are integral types.
inline bool BothIntegral(TypeTag t1, TypeTag t2)
	{
	return (IsIntegral(t1) && IsIntegral(t2));
	}

// True if both tags are arithmetic types.
inline bool BothArithmetic(TypeTag t1, TypeTag t2)
	{
	return (IsArithmetic(t1) && IsArithmetic(t2));
	}

// True if either tags is an arithmetic type.
inline bool EitherArithmetic(TypeTag t1, TypeTag t2)
	{
	return (IsArithmetic(t1) || IsArithmetic(t2));
	}

// True if both tags are boolean types.
inline bool BothBool(TypeTag t1, TypeTag t2)
	{
	return (IsBool(t1) && IsBool(t2));
	}

// True if both tags are interval types.
inline bool BothInterval(TypeTag t1, TypeTag t2)
	{
	return (IsInterval(t1) && IsInterval(t2));
	}

// True if both tags are string types.
inline bool BothString(TypeTag t1, TypeTag t2)
	{
	return (IsString(t1) && IsString(t2));
	}

// True if either tag is the error type.
inline bool EitherError(TypeTag t1, TypeTag t2)
	{
	return (IsErrorType(t1) || IsErrorType(t2));
	}

// Returns the basic (non-parameterized) type with the given type.
const TypePtr& base_type(TypeTag tag);

// Returns the basic error type.
inline const TypePtr& error_type()
	{
	return base_type(TYPE_ERROR);
	}

	} // namespace zeek

extern zeek::OpaqueTypePtr md5_type;
extern zeek::OpaqueTypePtr sha1_type;
extern zeek::OpaqueTypePtr sha256_type;
extern zeek::OpaqueTypePtr entropy_type;
extern zeek::OpaqueTypePtr cardinality_type;
extern zeek::OpaqueTypePtr topk_type;
extern zeek::OpaqueTypePtr bloomfilter_type;
extern zeek::OpaqueTypePtr x509_opaque_type;
extern zeek::OpaqueTypePtr ocsp_resp_opaque_type;
extern zeek::OpaqueTypePtr paraglob_type;
extern zeek::OpaqueTypePtr int_counter_metric_type;
extern zeek::OpaqueTypePtr int_counter_metric_family_type;
extern zeek::OpaqueTypePtr dbl_counter_metric_type;
extern zeek::OpaqueTypePtr dbl_counter_metric_family_type;
extern zeek::OpaqueTypePtr int_gauge_metric_type;
extern zeek::OpaqueTypePtr int_gauge_metric_family_type;
extern zeek::OpaqueTypePtr dbl_gauge_metric_type;
extern zeek::OpaqueTypePtr dbl_gauge_metric_family_type;
extern zeek::OpaqueTypePtr int_histogram_metric_type;
extern zeek::OpaqueTypePtr int_histogram_metric_family_type;
extern zeek::OpaqueTypePtr dbl_histogram_metric_type;
extern zeek::OpaqueTypePtr dbl_histogram_metric_family_type;