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Re: Export bits of the demangler's internal interface


Daniel Jacobowitz <drow@mvista.com> writes:

> Yes, but it turns out that it was an almost perfect interface for what
> I needed - witness the total size of the changes I had to make, which
> is actually quite small.  If I had to design an interface for this
> (something which I was never especially good at), it would look pretty
> much the same.  If there's something you'd prefer, you'll have to
> suggest it yourself :)

What do you (and DJ, and anybody else) think about this sort of
interface?

I would envision putting this in demangle.h, rather than creating a
new header file.

This pushes the issue of memory allocation onto the caller, rather
than exporting the d_info structure which is used internally but has
little relevance for your purposes.

I considered hiding struct demangle_component and providing accessor
functions, but I decided that that wasn't worth it.  I don't think we
need to worry about binary compatibility among different releases.  I
hid the other structures because there was no present need to expose
them.  Your code only uses them to check for a void parameter to a
function, and you can solve that in other ways.

Ian

/* The V3 demangler works in two passes.  The first pass builds a tree
   representation of the mangled name, and the second pass turns the
   tree representation into a demangled string.  Here we define an
   interface to permit a caller to build their own tree
   representation, which they can pass to the demangler to get a
   demangled string.  This can be used to canonicalize user input into
   something which the demangler might output.  It could also be used
   by other demanglers in the future.  */

/* These are the component types which may be found in the tree.  Many
   component types have one or two subtrees, referred to as left and
   right (a component type with only one subtree puts it in the left
   subtree).  */

enum demangle_component_type
{
  /* A name, with a length and a pointer to a string.  */
  DEMANGLE_COMPONENT_NAME,
  /* A qualified name.  The left subtree is a class or namespace or
     some such thing, and the right subtree is a name qualified by
     that class.  */
  DEMANGLE_COMPONENT_QUAL_NAME,
  /* A local name.  The left subtree describes a function, and the
     right subtree is a name which is local to that function.  */
  DEMANGLE_COMPONENT_LOCAL_NAME,
  /* A typed name.  The left subtree is a name, and the right subtree
     describes that name as a function.  */
  DEMANGLE_COMPONENT_TYPED_NAME,
  /* A template.  The left subtree is a template name, and the right
     subtree is a template argument list.  */
  DEMANGLE_COMPONENT_TEMPLATE,
  /* A template parameter.  This holds a number, which is the template
     parameter index.  */
  DEMANGLE_COMPONENT_TEMPLATE_PARAM,
  /* A constructor.  This holds a name and the kind of
     constructor.  */
  DEMANGLE_COMPONENT_CTOR,
  /* A destructor.  This holds a name and the kind of destructor.  */
  DEMANGLE_COMPONENT_DTOR,
  /* A vtable.  This has one subtree, the type for which this is a
     vtable.  */
  DEMANGLE_COMPONENT_VTABLE,
  /* A VTT structure.  This has one subtree, the type for which this
     is a VTT.  */
  DEMANGLE_COMPONENT_VTT,
  /* A construction vtable.  The left subtree is the type for which
     this is a vtable, and the right subtree is the derived type for
     which this vtable is built.  */
  DEMANGLE_COMPONENT_CONSTRUCTION_VTABLE,
  /* A typeinfo structure.  This has one subtree, the type for which
     this is the tpeinfo structure.  */
  DEMANGLE_COMPONENT_TYPEINFO,
  /* A typeinfo name.  This has one subtree, the type for which this
     is the typeinfo name.  */
  DEMANGLE_COMPONENT_TYPEINFO_NAME,
  /* A typeinfo function.  This has one subtree, the type for which
     this is the tpyeinfo function.  */
  DEMANGLE_COMPONENT_TYPEINFO_FN,
  /* A thunk.  This has one subtree, the name for which this is a
     thunk.  */
  DEMANGLE_COMPONENT_THUNK,
  /* A virtual thunk.  This has one subtree, the name for which this
     is a virtual thunk.  */
  DEMANGLE_COMPONENT_VIRTUAL_THUNK,
  /* A covariant thunk.  This has one subtree, the name for which this
     is a covariant thunk.  */
  DEMANGLE_COMPONENT_COVARIANT_THUNK,
  /* A Java class.  This has one subtree, the type.  */
  DEMANGLE_COMPONENT_JAVA_CLASS,
  /* A guard variable.  This has one subtree, the name for which this
     is a guard variable.  */
  DEMANGLE_COMPONENT_GUARD,
  /* A reference temporary.  This has one subtree, the name for which
     this is a temporary.  */
  DEMANGLE_COMPONENT_REFTEMP,
  /* A standard substitution.  This holds the name of the
     substitution.  */
  DEMANGLE_COMPONENT_SUB_STD,
  /* The restrict qualifier.  The one subtree is the type which is
     being qualified.  */
  DEMANGLE_COMPONENT_RESTRICT,
  /* The volatile qualifier.  The one subtree is the type which is
     being qualified.  */
  DEMANGLE_COMPONENT_VOLATILE,
  /* The const qualifier.  The one subtree is the type which is being
     qualified.  */
  DEMANGLE_COMPONENT_CONST,
  /* The restrict qualifier modifying a member function.  The one
     subtree is the type which is being qualified.  */
  DEMANGLE_COMPONENT_RESTRICT_THIS,
  /* The volatile qualifier modifying a member function.  The one
     subtree is the type which is being qualified.  */
  DEMANGLE_COMPONENT_VOLATILE_THIS,
  /* The const qualifier modifying a member function.  The one subtree
     is the type which is being qualified.  */
  DEMANGLE_COMPONENT_CONST_THIS,
  /* A vendor qualifier.  The left subtree is the type which is being
     qualified, and the right subtree is the name of the
     qualifier.  */
  DEMANGLE_COMPONENT_VENDOR_TYPE_QUAL,
  /* A pointer.  The one subtree is the type which is being pointed
     to.  */
  DEMANGLE_COMPONENT_POINTER,
  /* A reference.  The one subtree is the type which is being
     referenced.  */
  DEMANGLE_COMPONENT_REFERENCE,
  /* A complex type.  The one subtree is the base type.  */
  DEMANGLE_COMPONENT_COMPLEX,
  /* An imaginary type.  The one subtree is the base type.  */
  DEMANGLE_COMPONENT_IMAGINARY,
  /* A builtin type.  This holds the builtin type information.  */
  DEMANGLE_COMPONENT_BUILTIN_TYPE,
  /* A vendor's builtin type.  This holds the name of the type.  */
  DEMANGLE_COMPONENT_VENDOR_TYPE,
  /* A function type.  The left subtree is the return type.  The right
     subtree is a list of ARGLIST nodes.  Either or both may be
     NULL.  */
  DEMANGLE_COMPONENT_FUNCTION_TYPE,
  /* An array type.  The left subtree is the dimension, which may be
     NULL, or a string (represented as DEMANGLE_COMPONENT_NAME), or an
     expression.  The right subtree is the element type.  */
  DEMANGLE_COMPONENT_ARRAY_TYPE,
  /* A pointer to member type.  The left subtree is the class type,
     and the right subtree is the member type.  CV-qualifiers appear
     on the latter.  */
  DEMANGLE_COMPONENT_PTRMEM_TYPE,
  /* An argument list.  The left subtree is the current argument, and
     the right subtree is either NULL or another ARGLIST node.  */
  DEMANGLE_COMPONENT_ARGLIST,
  /* A template argument list.  The left subtree is the current
     template argument, and the right subtree is either NULL or
     another TEMPLATE_ARGLIST node.  */
  DEMANGLE_COMPONENT_TEMPLATE_ARGLIST,
  /* An operator.  This holds information about a standard
     operator.  */
  DEMANGLE_COMPONENT_OPERATOR,
  /* An extended operator.  This holds the number of arguments, and
     the name of the extended operator.  */
  DEMANGLE_COMPONENT_EXTENDED_OPERATOR,
  /* A typecast, represented as a unary operator.  The one subtree is
     the type to which the argument should be cast.  */
  DEMANGLE_COMPONENT_CAST,
  /* A unary expression.  The left subtree is the operator, and the
     right subtree is the single argument.  */
  DEMANGLE_COMPONENT_UNARY,
  /* A binary expression.  The left subtree is the operator, and the
     right subtree is a BINARY_ARGS.  */
  DEMANGLE_COMPONENT_BINARY,
  /* Arguments to a binary expression.  The left subtree is the first
     argument, and the right subtree is the second argument.  */
  DEMANGLE_COMPONENT_BINARY_ARGS,
  /* A trinary expression.  The left subtree is the operator, and the
     right subtree is a TRINARY_ARG1.  */
  DEMANGLE_COMPONENT_TRINARY,
  /* Arguments to a trinary expression.  The left subtree is the first
     argument, and the right subtree is a TRINARY_ARG2.  */
  DEMANGLE_COMPONENT_TRINARY_ARG1,
  /* More arguments to a trinary expression.  The left subtree is the
     second argument, and the right subtree is the third argument.  */
  DEMANGLE_COMPONENT_TRINARY_ARG2,
  /* A literal.  The left subtree is the type, and the right subtree
     is the value, represented as a DEMANGLE_COMPONENT_NAME.  */
  DEMANGLE_COMPONENT_LITERAL,
  /* A negative literal.  Like LITERAL, but the value is negated.
     This is a minor hack: the NAME used for LITERAL points directly
     to the mangled string, but since negative numbers are mangled
     using 'n' instead of '-', we want a way to indicate a negative
     number which involves neither modifying the mangled string nor
     allocating a new copy of the literal in memory.  */
  DEMANGLE_COMPONENT_LITERAL_NEG
};

/* Types which are only used internally.  */

struct demangle_operator_info;
struct demangle_builtin_type_info;

/* A node in the tree representation is an instance of a struct
   demangle_component.  The representation of that struct is
   hidden--callers may only create and access it via functions defined
   here.

   Note that the field names of the struct are not well protected
   against macros defined by the file including this one.  We can fix
   this if it ever becomes a problem.  */

struct demangle_component
{
  /* The type of this component.  */
  enum demangle_component_type type;

  union
  {
    /* For DEMANGLE_COMPONENT_NAME.  */
    struct
    {
      /* A pointer to the name (which need not NULL terminated) and
	 its length.  */
      const char *s;
      int len;
    } s_name;

    /* For DEMANGLE_COMPONENT_OPERATOR.  */
    struct
    {
      /* Operator.  */
      const struct demangle_operator_info *op;
    } s_operator;

    /* For DEMANGLE_COMPONENT_EXTENDED_OPERATOR.  */
    struct
    {
      /* Number of arguments.  */
      int args;
      /* Name.  */
      struct demangle_component *name;
    } s_extended_operator;

    /* For DEMANGLE_COMPONENT_CTOR.  */
    struct
    {
      /* Kind of constructor.  */
      enum gnu_v3_ctor_kinds kind;
      /* Name.  */
      struct demangle_component *name;
    } s_ctor;

    /* For DEMANGLE_COMPONENT_DTOR.  */
    struct
    {
      /* Kind of destructor.  */
      enum gnu_v3_dtor_kinds kind;
      /* Name.  */
      struct demangle_component *name;
    } s_dtor;

    /* For DEMANGLE_COMPONENT_BUILTIN_TYPE.  */
    struct
    {
      /* Builtin type.  */
      const struct demangle_builtin_type_info *type;
    } s_builtin;

    /* For DEMANGLE_COMPONENT_SUB_STD.  */
    struct
    {
      /* Standard substitution string.  */
      const char* string;
      /* Length of string.  */
      int len;
    } s_string;

    /* For DEMANGLE_COMPONENT_TEMPLATE_PARAM.  */
    struct
    {
      /* Template parameter index.  */
      long number;
    } s_number;

    /* For other types.  */
    struct
    {
      /* Left (or only) subtree.  */
      struct demangle_component *left;
      /* Right subtree.  */
      struct demangle_component *right;
    } s_binary;

  } u;
};

/* People building mangled trees are expected to allocate instances of
   struct demangle_component themselves.  They can then call one of
   the following functions to fill them in.  */

/* Fill in most component types with a left subtree and a right
   subtree.  Returns non-zero on success, zero on failure, such as an
   unrecognized or inappropriate component type.  */

extern int
cplus_demangle_fill_component PARAMS ((struct demangle_component *fill,
				       enum demangle_component_type,
				       struct demangle_component *left,
				       struct demangle_component *right));

/* Fill in a DEMANGLE_COMPONENT_NAME.  Always returns non-zero.  */

extern int
cplus_demangle_fill_name PARAMS ((struct demangle_component *fill,
				  const char *, int));

/* Fill in a DEMANGLE_COMPONENT_BUILTIN_TYPE, using the name of the
   builtin type (e.g., "int", etc.).  Returns non-zero on success,
   zero if the type is not recognized.  */

extern int
cplus_demangle_fill_builtin_type PARAMS ((struct demangle_component *fill,
					  const char *typename));

/* Fill in a DEMANGLE_COMPONENT_OPERATOR, using the name of the
   operator.  Returns non-zero on success, zero if the operator is not
   recognized.  */

extern int
cplus_demangle_fill_operator PARAMS ((struct demangle_component *fill,
				      const char *opname));

/* Fill in a DEMANGLE_COMPONENT_EXTENDED_OPERATOR, providing the
   number of arguments and the name.  Returns non-zero on success,
   zero for bad arguments.  */

extern int
cplus_demangle_fill_extended_operator PARAMS ((struct demangle_component *fill,
					       int numargs,
					       struct demangle_component *nm));

/* Fill in a DEMANGLE_COMPONENT_CTOR.  Returns non-zero on success,
   zero for bad arguments.  */

extern int
cplus_demangle_fill_ctor PARAMS ((struct demangle_component *fill,
				  enum gnu_v3_ctor_kinds kind,
				  struct demangle_component *name));

/* Fill in a DEMANGLE_COMPONENT_DTOR.  Returns non-zero on success,
   zero for bad arguments.  */

extern int
cplus_demangle_fill_dtor PARAMS ((struct demangle_component *fill,
				  enum gnu_v3_dtor_kinds kind,
				  struct demangle_component *name));

/* This function takes a struct demangle_component tree and returns
   the corresponding demangled string.  The first argument is DMGL_*
   options.  The second is the tree to demangle.  The third is a guess
   at the length of the demangled string, used to initially allocate
   the return buffer.  The fourth is a pointer to a size_t.  On
   success, this function returns a buffer allocated by malloc(), and
   sets the size_t pointed to by the fourth argument to the size of
   the allocated buffer (not the length of the returned string).  On
   failure, this function returns NULL, and sets the size_t pointed to
   by the fourth argument to 0 for an invalid tree, or to 1 for a
   memory allocation error.  */

extern char *
cplus_demangle_print PARAMS ((int options,
			      const struct demangle_component *tree,
			      int estimated_length,
			      size_t *p_allocated_size));


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