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Fixed size buffers in expressions



Member lookup (§7.3) of a fixed size buffer member proceeds exactly like member lookup of a field.

A fixed size buffer can be referenced in an expression using a simple-name (§7.5.2) or a member-access (§7.5.4).

When a fixed size buffer member is referenced as a simple name, the effect is the same as a member access of the form this.I, where I is the fixed size buffer member.

In a member access of the form E.I, if E is of a struct type and a member lookup of I in that struct type identifies a fixed size member, then E.I is evaluated an classified as follows:

· If the expression E.I does not occur in an unsafe context, a compile-time error occurs.

· If E is classified as a value, a compile-time error occurs.

· Otherwise, if E is a moveable variable (§18.3) and the expression E.I is not a fixed-pointer-initializer (§18.6), a compile-time error occurs.

· Otherwise, E references a fixed variable and the result of the expression is a pointer to the first element of the fixed size buffer member I in E. The result is of type S*, where S is the element type of I, and is classified as a value.

The subsequent elements of the fixed size buffer can be accessed using pointer operations from the first element. Unlike access to arrays, access to the elements of a fixed size buffer is an unsafe operation and is not range checked.

The following example declares and uses a struct with a fixed size buffer member.

unsafe struct Font
{
public int size;
public fixed char name[32];
}

class Test
{
unsafe static void PutString(string s, char* buffer, int bufSize) {
int len = s.Length;
if (len > bufSize) len = bufSize;
for (int i = 0; i < len; i++) buffer[i] = s[i];
for (int i = len; i < bufSize; i++) buffer[i] = (char)0;
}

unsafe static void Main()
{
Font f;
f.size = 10;
PutString("Times New Roman", f.name, 32);
}
}

Definite assignment checking

Fixed size buffers are not subject to definite assignment checking (§5.3), and fixed size buffer members are ignored for purposes of definite assignment checking of struct type variables.

When the outermost containing struct variable of a fixed size buffer member is a static variable, an instance variable of a class instance, or an array element, the elements of the fixed size buffer are automatically initialized to their default values (§5.2). In all other cases, the initial content of a fixed size buffer is undefined.

Stack allocation

In an unsafe context, a local variable declaration (§8.5.1) may include a stack allocation initializer which allocates memory from the call stack.

local-variable-initializer:

stackalloc-initializer

stackalloc-initializer:
stackalloc unmanaged-type [ expression ]

The unmanaged-type indicates the type of the items that will be stored in the newly allocated location, and the expression indicates the number of these items. Taken together, these specify the required allocation size. Since the size of a stack allocation cannot be negative, it is a compile-time error to specify the number of items as a constant-expression that evaluates to a negative value.

A stack allocation initializer of the form stackalloc T[E] requires T to be an unmanaged type (§18.2) and E to be an expression of type int. The construct allocates E * sizeof(T) bytes from the call stack and returns a pointer, of type T*, to the newly allocated block. If E is a negative value, then the behavior is undefined. If E is zero, then no allocation is made, and the pointer returned is implementation-defined. If there is not enough memory available to allocate a block of the given size, a System.StackOverflowException is thrown.

The content of the newly allocated memory is undefined.

Stack allocation initializers are not permitted in catch or finally blocks (§8.10).

There is no way to explicitly free memory allocated using stackalloc. All stack allocated memory blocks created during the execution of a function member are automatically discarded when that function member returns. This corresponds to the alloca function, an extension commonly found in C and C++ implementations.

In the example

using System;

class Test
{
static string IntToString(int value) {
int n = value >= 0? value: -value;
unsafe {
char* buffer = stackalloc char[16];
char* p = buffer + 16;
do {
*--p = (char)(n % 10 + '0');
n /= 10;
} while (n != 0);
if (value < 0) *--p = '-';
return new string(p, 0, (int)(buffer + 16 - p));
}
}

static void Main() {
Console.WriteLine(IntToString(12345));
Console.WriteLine(IntToString(-999));
}
}

a stackalloc initializer is used in the IntToString method to allocate a buffer of 16 characters on the stack. The buffer is automatically discarded when the method returns.

Dynamic memory allocation

Except for the stackalloc operator, C# provides no predefined constructs for managing non-garbage collected memory. Such services are typically provided by supporting class libraries or imported directly from the underlying operating system. For example, the Memory class below illustrates how the heap functions of an underlying operating system might be accessed from C#:

using System;
using System.Runtime.InteropServices;

public unsafe class Memory
{
// Handle for the process heap. This handle is used in all calls to the
// HeapXXX APIs in the methods below.

static int ph = GetProcessHeap();

// Private instance constructor to prevent instantiation.

private Memory() {}

// Allocates a memory block of the given size. The allocated memory is
// automatically initialized to zero.

public static void* Alloc(int size) {
void* result = HeapAlloc(ph, HEAP_ZERO_MEMORY, size);
if (result == null) throw new OutOfMemoryException();
return result;
}

// Copies count bytes from src to dst. The source and destination
// blocks are permitted to overlap.

public static void Copy(void* src, void* dst, int count) {
byte* ps = (byte*)src;
byte* pd = (byte*)dst;
if (ps > pd) {
for (; count != 0; count--) *pd++ = *ps++;
}
else if (ps < pd) {
for (ps += count, pd += count; count != 0; count--) *--pd = *--ps;
}
}

// Frees a memory block.

public static void Free(void* block) {
if (!HeapFree(ph, 0, block)) throw new InvalidOperationException();
}

// Re-allocates a memory block. If the reallocation request is for a
// larger size, the additional region of memory is automatically
// initialized to zero.

public static void* ReAlloc(void* block, int size) {
void* result = HeapReAlloc(ph, HEAP_ZERO_MEMORY, block, size);
if (result == null) throw new OutOfMemoryException();
return result;
}

// Returns the size of a memory block.

public static int SizeOf(void* block) {
int result = HeapSize(ph, 0, block);
if (result == -1) throw new InvalidOperationException();
return result;
}

// Heap API flags

const int HEAP_ZERO_MEMORY = 0x00000008;

// Heap API functions

[DllImport("kernel32")]
static extern int GetProcessHeap();

[DllImport("kernel32")]
static extern void* HeapAlloc(int hHeap, int flags, int size);

[DllImport("kernel32")]
static extern bool HeapFree(int hHeap, int flags, void* block);

[DllImport("kernel32")]
static extern void* HeapReAlloc(int hHeap, int flags,
void* block, int size);

[DllImport("kernel32")]
static extern int HeapSize(int hHeap, int flags, void* block);
}

An example that uses the Memory class is given below:

class Test
{
static void Main() {
unsafe {
byte* buffer = (byte*)Memory.Alloc(256);
try {
for (int i = 0; i < 256; i++) buffer[i] = (byte)i;
byte[] array = new byte[256];
fixed (byte* p = array) Memory.Copy(buffer, p, 256);
}
finally {
Memory.Free(buffer);
}
for (int i = 0; i < 256; i++) Console.WriteLine(array[i]);
}
}
}

The example allocates 256 bytes of memory through Memory.Alloc and initializes the memory block with values increasing from 0 to 255. It then allocates a 256 element byte array and uses Memory.Copy to copy the contents of the memory block into the byte array. Finally, the memory block is freed using Memory.Free and the contents of the byte array are output on the console.


A. Documentation comments

C# provides a mechanism for programmers to document their code using a special comment syntax that contains XML text. In source code files, comments having a certain form can be used to direct a tool to produce XML from those commentsand the source code elements, which they precede. Comments using such syntax are called documentation comments. They must immediately precede a user-defined type (such as a class, delegate, or interface) or a member (such as a field, event, property, or method). The XML generation tool is called the documentation generator.(This generator could be, but need not be, the C# compiler itself.) The output produced by the documentation generator is called the documentation file.A documentation file is used as input to a documentation viewer;a tool intended to produce some sort of visual display of type information and its associated documentation.

This specification suggests a set of tags to be used in documentation comments, but use of these tags is not required, and other tags may be used if desired, as long the rules of well-formed XML are followed.

A.1 Introduction

Comments having a special form can be used to direct a tool to produce XML from those commentsand the source code elements, which they precede. Such comments are single-line comments that start with three slashes (///), or delimited comments that start with a slash and two stars (/**). They must immediately precede a user-defined type (such as a class, delegate, or interface) or a member (such as a field, event, property, or method) that they annotate. Attribute sections (§17.2) are considered part of declarations, so documentation comments must precede attributes applied to a type or member.

Syntax:

single-line-doc-comment:
/// input-charactersopt

delimited-doc-comment:
/** delimited-comment-textopt */

In a single-line-doc-comment, if there is a whitespace character following the /// characters on each of the single-line-doc-comments adjacent to the current single-line-doc-comment, then that whitespace character is not included in the XML output.

In a delimited-doc-comment, if the first non-whitespace character on the second line is an asterisk and the same pattern of optional whitespace characters and an asterisk character is repeated at the beginning of each of the line within the delimited-doc-comment, then the characters of the repeated pattern are not included in the XML output. The pattern may include whitespace characters after, as well as before, the asterisk character.

Example:

/// <summary>Class <c>Point</c> models a point in a two-dimensional
/// plane.</summary>
///
public class Point
{
/// <summary>method <c>draw</c> renders the point.</summary>
void draw() {…}
}

The text within documentation comments must be well formed according to the rules of XML (http://www.w3.org/TR/REC-xml). If the XML is ill formed, a warning is generated and the documentation file will contain a comment saying that an error was encountered.

Although developers are free to create their own set of tags, a recommended set is defined in §A.2. Some of the recommended tags have special meanings:

· The <param> tag is used to describe parameters. If such a tag is used, the documentation generator must verify that the specified parameter exists and that all parameters are described in documentation comments. If such verification fails, the documentation generator issues a warning.

· The crefattribute can be attached to any tag to provide a reference to a code element. The documentation generator must verify that this code element exists. If the verification fails, the documentation generator issues a warning. When looking for a name described in a cref attribute, the documentation generator must respect namespace visibility according to using statements appearing within the source code. For code elements that are generic, the normal generic syntax (ie “List<T>”) cannot be used because it produces invalid XML. Braces can be used instead of brackets (ie “List{T}”), or the XML escape syntax can be used (ie “List&lt;T&gt;”).

· The <summary> tag is intended to be used by a documentation viewer to display additional information about a type or member.

· The <include> tag includes information from an external XML file.

Note carefully that the documentation file does not provide full information about the type and members (for example, it does not contain any type information). To get such information about a type or member, the documentation file must be used in conjunction with reflection on the actual type or member.

A.2 Recommended tags

The documentation generator must accept and process any tag that is valid according to the rules of XML. The following tags provide commonly used functionality in user documentation. (Of course, other tags are possible.)

 

Tag Section Purpose
<c> A.2.1 Set text in a code-like font
<code> A.2.2 Set one or more lines of source code or program output
<example> A.2.3 Indicate an example
<exception> A.2.4 Identifies the exceptions a method can throw
<include> A.2.5 Includes XML from an external file
<list> A.2.6 Create a list or table
<para> A.2.7 Permit structure to be added to text
<param> A.2.8 Describe a parameter for a method or constructor
<paramref> A.2.9 Identify that a word is a parameter name
<permission> A.2.10 Document the security accessibility of a member
<remark> A.2.11 Describe additional information about a type
<returns> A.2.12 Describe the return value of a method
<see> A.2.13 Specify a link
<seealso> A.2.14 Generate a See Also entry
<summary> A.2.15 Describe a type or a member of a type
<value> A.2.16 Describe a property
<typeparam>   Describe a generic type parameter
<typeparamref>   Identify that a word is a type parameter name

 

A.2.1 <c>

This tag provides a mechanism to indicate that a fragment of text within a description should be set in a special font such as that used for a block of code. For lines of actual code, use <code> (§A.2.2).

Syntax:

<c>text</c>

Example:

/// <summary>Class <c>Point</c> models a point in a two-dimensional
/// plane.</summary>

public class Point
{
// ...
}

A.2.2 <code>

This tag is used to set one or more lines of source code or program output in some special font. For small code fragments in narrative, use <c> (§A.2.1).

Syntax:

<code>source code or program output</code>

Example:

/// <summary>This method changes the point's location by
/// the given x- and y-offsets.
/// <example>For example:
/// <code>
/// Point p = new Point(3,5);
/// p.Translate(-1,3);
/// </code>
/// results in <c>p</c>'s having the value (2,8).
/// </example>
/// </summary>

public void Translate(int xor, int yor) {
X += xor;
Y += yor;
}

A.2.3 <example>

This tag allows example code within a comment, to specify how a method or other library member may be used. Ordinarily, this would also involve use of the tag <code> (§A.2.2) as well.

Syntax:

<example>description</example>

Example:

See <code> (§A.2.2) for an example.

A.2.4 <exception>

This tag provides a way to document the exceptions a method can throw.

Syntax:

<exception cref="member">description</exception>

where

cref="member"

The name of a member. The documentation generator checks that the given member exists and translates member to the canonical element name in the documentation file.

description

A description of the circumstances in which the exception is thrown.

Example:

public class DataBaseOperations
{
/// <exception cref="MasterFileFormatCorruptException"></exception>
/// <exception cref="MasterFileLockedOpenException"></exception>
public static void ReadRecord(int flag) {
if (flag == 1)
throw new MasterFileFormatCorruptException();
else if (flag == 2)
throw new MasterFileLockedOpenException();
// …
}
}

A.2.5 <include>

This tag allows including information from an XML document that is external to the source code file. The external file must be a well-formed XML document, and an XPath expression is applied to that document to specify what XML from that document to include. The <include> tag is then replaced with the selected XML from the external document.

Syntax:

<include file="filename" path="xpath" />

where

file="filename"

The file name of an external XML file. The file name is interpreted relative to the file that contains the include tag.

path="xpath"

An XPath expression that selects some of the XML in the external XML file.

Example:

If the source code contained a declaration like:

/// <include file="docs.xml" path='extradoc/class[@name="IntList"]/*' />
public class IntList { … }

and the external file “docs.xml” had the following contents:

<?xml version="1.0"?>
<extradoc>
<class name=
"IntList">
<summary>
Contains a list of integers.
</summary>
</class>
<class name=
"StringList">
<summary>
Contains a list of integers.
</summary>
</class>
</extradoc>

then the same documentation is output as if the source code contained:

/// <summary>
/// Contains a list of integers.
/// </summary>
public class IntList { … }

A.2.6 <list>

This tag is used to create a list or table of items. It may contain a <listheader> block to define the heading row of either a table or definition list. (When defining a table, only an entry for term in the heading need be supplied.)

Each item in the list is specified with an <item> block. When creating a definition list, both term and description must be specified. However, for a table, bulleted list, or numbered list, only description need be specified.

Syntax:

<list type="bullet" | "number" | "table">
<listheader>
<term>term</term>
<description>description</description>
</listheader>
<item>
<term>term</term>
<description>description</description>
</item>

<item>
<term>term</term>
<description>description</description>
</item>
</list>

where

term

The term to define, whose definition is in description.

description

Either an item in a bullet or numbered list, or the definition of a term.

Example:

public class MyClass
{
/// <summary>Here is an example of a bulleted list:
/// <list type="bullet">
/// <item>
/// <description>Item 1.</description>
/// </item>
/// <item>
/// <description>Item 2.</description>
/// </item>
/// </list>
/// </summary>
public static void Main () {
// ...
}
}

A.2.7 <para>

This tag is for use inside other tags, such as <summary> (§A.2.11) or <returns> (§A.2.12), and permits structure to be added to text.

Syntax:

<para>content</para>

where

content

The text of the paragraph.

Example:

/// <summary>This is the entry point of the Point class testing program.
/// <para>This program tests each method and operator, and
/// is intended to be run after any non-trvial maintenance has
/// been performed on the Point class.</para></summary>
public static void Main() {
// ...
}

A.2.8 <param>

This tag is used to describe a parameter for a method, constructor, or indexer.

Syntax:

<param name="name">description</param>

where

name

The name of the parameter.

description

A description of the parameter.

Example:

/// <summary>This method changes the point's location to
/// the given coordinates.</summary>
/// <param name="xor">the new x-coordinate.</param>
/// <param name="yor">the new y-coordinate.</param>
public void Move(int xor, int yor) {
X = xor;
Y = yor;
}

A.2.9 <paramref>

This tag is used to indicate that a word is a parameter. The documentation file can be processed to format this parameter in some distinct way.

Syntax:

<paramref name="name"/>

where

name

The name of the parameter.

Example:

/// <summary>This constructor initializes the new Point to
/// (<paramref name="xor"/>,<paramref name="yor"/>).</summary>
/// <param name="xor">the new Point's x-coordinate.</param>
/// <param name="yor">the new Point's y-coordinate.</param>

public Point(int xor, int yor) {
X = xor;
Y = yor;
}

A.2.10 <permission>

This tag allows the security accessibility of a member to be documented.

Syntax:

<permission cref="member">description</permission>

where

cref="member"

The name of a member. The documentation generator checks that the given code element exists and translates member to the canonical element name in the documentation file.

description

A description of the access to the member.

Example:

/// <permission cref="System.Security.PermissionSet">Everyone can
/// access this method.</permission>

public static void Test() {
// ...
}

A.2.11 <remark>

This tag is used to specify extra information about a type. (Use <summary> (§A.2.15) to describe the type itself and the members of a type.)

Syntax:

<remark>description</remark>

where

description

The text of the remark.

Example:

/// <summary>Class <c>Point</c> models a point in a
/// two-dimensional plane.</summary>
/// <remark>Uses polar coordinates</remark>
public class Point
{
// ...
}

A.2.12 <returns>

This tag is used to describe the return value of a method.

Syntax:

<returns>description</returns>

where

description

A description of the return value.

Example:

/// <summary>Report a point's location as a string.</summary>
/// <returns>A string representing a point's location, in the form (x,y),
/// without any leading, trailing, or embedded whitespace.</returns>
public override string ToString() {
return "(" + X + "," + Y + ")";
}

A.2.13 <see>

This tag allows a link to be specified within text. Use <seealso> (§A.2.14) to indicate text that is to appear in a See Also section.

Syntax:

<see cref="member"/>

where

cref="member"

The name of a member. The documentation generator checks that the given code element exists and changes member to the element name in the generated documentation file.

Example:

/// <summary>This method changes the point's location to
/// the given coordinates.</summary>
/// <see cref="Translate"/>
public void Move(int xor, int yor) {
X = xor;
Y = yor;
}

/// <summary>This method changes the point's location by
/// the given x- and y-offsets.
/// </summary>
/// <see cref="Move"/>
public void Translate(int xor, int yor) {
X += xor;
Y += yor;
}

A.2.14 <seealso>

This tag allows an entry to be generated for the See Also section. Use <see> (§A.2.13) to specify a link from within text.

Syntax:

<seealso cref="member"/>

where

cref="member"

The name of a member. The documentation generator checks that the given code element exists and changes member to the element name in the generated documentation file.

Example:

/// <summary>This method determines whether two Points have the same
/// location.</summary>
/// <seealso cref="operator=="/>
/// <seealso cref="operator!="/>
public override bool Equals(object o) {
// ...
}

A.2.15 <summary>

This tag can be used to describe a type or a member of a type. Use <remark> (§A.2.11) to describe the type itself.

Syntax:

<summary>description</summary>

where

description

A summary of the type or member.

Example:

/// <summary>This constructor initializes the new Point to (0,0).</summary>
public Point() : this(0,0) {
}

A.2.16 <value>

This tag allows a property to be described.

Syntax:

<value>property description</value>

where

property description

A description for the property.

Example:

/// <value>Property <c>X</c> represents the point's x-coordinate.</value>
public int X
{
get { return x; }
set { x = value; }
}

A.2.17 <typeparam>

This tag is used to describe a generic type parameter for a class, struct, interface, delegate, or method.

Syntax:

<typeparam name="name">description</typeparam>

where

name

The name of the type parameter.

description

A description of the type parameter.

Example:

/// <summary>A generic list class.</summary>
/// <typeparam name="T">The type stored by the list.</typeparam>
public class MyList<T> {
...
}

A.2.18 <typeparamref>

This tag is used to indicate that a word is a type parameter. The documentation file can be processed to format this type parameter in some distinct way.

Syntax:

<typeparamref name="name"/>

where

name

The name of the type parameter.

Example:

/// <summary>This method fetches data and returns a list of <typeparamref name=”T”> ”/>”> .</summary>
/// <param name="string">query to execute</param>

public List<T> FetchData<T>(string query) {
...
}

A.3 Processing the documentation file

The documentation generator generates an ID stringfor each element in the source code that is tagged with a documentation comment. This ID string uniquely identifies a source element. A documentation viewer can use an ID string to identify the corresponding metadata/reflection item to which the documentation applies.

The documentation file is not a hierarchical representation of the source code; rather, it is a flat list with a generated ID string for each element.

A.3.1 ID string format

The documentation generator observes the following rules when it generates the ID strings:

· No white space is placed in the string.

· The first part of the string identifies the kind of member being documented, via a single character followed by a colon. The following kinds of members are defined:

 

Character Description
E Event
F Field
M Method (including constructors, destructors, and operators)
N Namespace
P Property (including indexers)
T Type (such as class, delegate, enum, interface, and struct)
! Error string; the rest of the string provides information about the error. For example, the documentation generator generates error information for links that cannot be resolved.

 

· The second part of the string is the fully qualified name of the element, starting at the root of the namespace. The name of the element, its enclosing type(s), and namespace are separated by periods. If the name of the item itself has periods, they are replaced by # (U+0023) characters. (It is assumed that no element has this character in its name.)

· For methods and properties with arguments, the argument list follows, enclosed in parentheses. For those without arguments, the parentheses are omitted. The arguments are separated by commas. The encoding of each argument is the same as a CLI signature, as follows:

o Arguments are represented by their documentation name, which is based on their fully qualified name, modified as follows:

Arguments that represent generic types have an appended “’” character followed by the number of type parameters

Arguments having the out or ref modifier have an @ following their type name. Arguments passed by value or via params have no special notation.

Arguments that are arrays are represented as [ lowerbound : size , … , lowerbound : size ] where the number of commas is the rank less one, and the lower bounds and size of each dimension, if known, are represented in decimal. If a lower bound or size is not specified, it is omitted. If the lower bound and size for a particular dimension are omitted, the “:” is omitted as well. Jagged arrays are represented by one “[]” per level.

Arguments that have pointer types other than void are represented using a * following the type name. A void pointer is represented using a type name of System.Void.

Arguments that refer to generic type parameters defined on types are encoded using the “`” character followed by the zero-based index of the type parameter.

Arguments that use generic type parameters defined in methods use a double-backtick “``” instead of the “`” used for types.

Arguments that refer to constructed generic types are encoded using the generic type, followed by “{“, followed by a comma-separated list of type arguments, followed by “}”.

A.3.2 ID string examples

The following examples each show a fragment of C# code, along with the ID string produced from each source element capable of having a documentation comment:

· Types are represented using their fully qualified name, augmented with generic information:

enum Color { Red, Blue, Green }

namespace Acme
{
interface IProcess {...}

struct ValueType {...}

class Widget: IProcess
{
public class NestedClass {...}

public interface IMenuItem {...}

public delegate void Del(int i);

public enum Direction { North, South, East, West }
}

class MyList<T>
{
class Helper<U,V> {...}
}
}

"T:Color"
"T:Acme.IProcess"
"T:Acme.ValueType"
"T:Acme.Widget"
"T:Acme.Widget.NestedClass"
"T:Acme.Widget.IMenuItem"
"T:Acme.Widget.Del"
"T:Acme.Widget.Direction"
”T:Acme.MyList`1”
”T:Acme.MyList`1.Helper`2”

· Fields are represented by their fully qualified name:

namespace Acme
{
struct ValueType
{
private int total;
}

class Widget: IProcess
{
public class NestedClass
{
private int value;
}

private string message;
private static Color defaultColor;
private const double PI = 3.14159;
protected readonly double monthlyAverage;
private long[] array1;
private Widget[,] array2;
private unsafe int *pCount;
private unsafe float **ppValues;
}
}

"F:Acme.ValueType.total"
"F:Acme.Widget.NestedClass.value"
"F:Acme.Widget.message"
"F:Acme.Widget.defaultColor"
"F:Acme.Widget.PI"
"F:Acme.Widget.monthlyAverage"
"F:Acme.Widget.array1"
"F:Acme.Widget.array2"
"F:Acme.Widget.pCount"
"F:Acme.Widget.ppValues"

· Constructors.

namespace Acme
{
class Widget: IProcess
{
static Widget() {...}

public Widget() {...}

public Widget(string s) {...}
}
}

"M:Acme.Widget.#cctor"
"M:Acme.Widget.#ctor"
"M:Acme.Widget.#ctor(System.String)"

· Destructors.

namespace Acme
{
class Widget: IProcess
{
~Widget() {...}
}
}

"M:Acme.Widget.Finalize"

· Methods.

namespace Acme
{
struct ValueType
{
public void M(int i) {...}
}

class Widget: IProcess
{
public class NestedClass
{
public void M(int i) {...}
}

public static void M0() {...}
public void M1(char c, out float f, ref ValueType v) {...}
public void M2(short[] x1, int[,] x2, long[][] x3) {...}
public void M3(long[][] x3, Widget[][,,] x4) {...}
public unsafe void M4(char *pc, Color **pf) {...}
public unsafe void M5(void *pv, double *[][,] pd) {...}
public void M6(int i, params object[] args) {...}
}

class MyList<T>
{
public void Test(T t) { }
}

class UseList
{
public void Process(MyList<int> list) { }
public MyList<T> GetValues<T>(T inputValue) { return null; }
}
}

"M:Acme.ValueType.M(System.Int32)"
"M:Acme.Widget.NestedClass.M(System.Int32)"
"M:Acme.Widget.M0"
"M:Acme.Widget.M1(System.Char,System.Single@,Acme.ValueType@)"
"M:Acme.Widget.M2(System.Int16[],System.Int32[0:,0:],System.Int64[][])"
"M:Acme.Widget.M3(System.Int64[][],Acme.Widget[0:,0:,0:][])"
"M:Acme.Widget.M4(System.Char*,Color**)"
"M:Acme.Widget.M5(System.Void*,System.Double*[0:,0:][])"
"M:Acme.Widget.M6(System.Int32,System.Object[])"
”M:Acme.MyList`1.Test(`0)”
”M:Acme.UseList.Process(Acme.MyList{System.Int32})”
”M:Acme.UseList.GetValues``(``0)”

· Properties and indexers.

namespace Acme
{
class Widget: IProcess
{
public int Width { get {...} set {...} }
public int this[int i] { get {...} set {...} }
public int this[string s, int i] { get {...} set {...} }
}
}

"P:Acme.Widget.Width"
"P:Acme.Widget.Item(System.Int32)"
"P:Acme.Widget.Item(System.String,System.Int32)"

· Events.

namespace Acme
{
class Widget: IProcess
{
public event Del AnEvent;
}
}

"E:Acme.Widget.AnEvent"

· Unary operators.

namespace Acme
{
class Widget: IProcess
{
public static Widget operator+(Widget x) {...}
}
}

"M:Acme.Widget.op_UnaryPlus(Acme.Widget)"

The complete set of unary operator function names used is as follows: op_UnaryPlus, op_UnaryNegation, op_LogicalNot, op_OnesComplement, op_Increment, op_Decrement, op_True, and op_False.

· Binary operators.

namespace Acme
{
class Widget: IProcess
{
public static Widget operator+(Widget x1, Widget x2) {...}
}
}

"M:Acme.Widget.op_Addition(Acme.Widget,Acme.Widget)"

The complete set of binary operator function names used is as follows: op_Addition, op_Subtraction, op_Multiply, op_Division, op_Modulus, op_BitwiseAnd, op_BitwiseOr, op_ExclusiveOr, op_LeftShift, op_RightShift, op_Equality, op_Inequality, op_LessThan, op_LessThanOrEqual, op_GreaterThan, and op_GreaterThanOrEqual.

· Conversion operators have a trailing “~” followed by the return type.

namespace Acme
{
class Widget: IProcess
{
public static explicit operator int(Widget x) {...}
public static implicit operator long(Widget x) {...}
}
}

"M:Acme.Widget.op_Explicit(Acme.Widget)~System.Int32"
"M:Acme.Widget.op_Implicit(Acme.Widget)~System.Int64"

A.4 An example

A.4.1 C# source code

The following example shows the source code of a Point class:

namespace Graphics
{

/// <summary>Class <c>Point</c> models a point in a two-dimensional plane.
/// </summary>
public class Point
{

/// <summary>Instance variable <c>x</c> represents the point's
/// x-coordinate.</summary>
private int x;

/// <summary>Instance variable <c>y</c> represents the point's
/// y-coordinate.</summary>
private int y;

/// <value>Property <c>X</c> represents the point's x-coordinate.</value>
public int X
{
get { return x; }
set { x = value; }
}

/// <value>Property <c>Y</c> represents the point's y-coordinate.</value>
public int Y
{
get { return y; }
set { y = value; }
}

/// <summary>This constructor initializes the new Point to
/// (0,0).</summary>
public Point() : this(0,0) {}

/// <summary>This constructor initializes the new Point to
/// (<paramref name="xor"/>,<paramref name="yor"/>).</summary>
/// <param><c>xor</c> is the new Point's x-coordinate.</param>
/// <param><c>yor</c> is the new Point's y-coordinate.</param>
public Point(int xor, int yor) {
X = xor;
Y = yor;
}

/// <summary>This method changes the point's location to
/// the given coordinates.</summary>
/// <param><c>xor</c> is the new x-coordinate.</param>
/// <param><c>yor</c> is the new y-coordinate.</param>
/// <see cref="Translate"/>
public void Move(int xor, int yor) {
X = xor;
Y = yor;
}

/// <summary>This method changes the point's location by
/// the given x- and y-offsets.
/// <example>For example:
/// <code>
/// Point p = new Point(3,5);
/// p.Translate(-1,3);
/// </code>
/// results in <c>p</c>'s having the value (2,8).
/// </example>
/// </summary>
/// <param><c>xor</c> is the relative x-offset.</param>
/// <param><c>yor</c> is the relative y-offset.</param>
/// <see cref="Move"/>
public void Translate(int xor, int yor) {
X += xor;
Y += yor;
}

/// <summary>This method determines whether two Points have the same
/// location.</summary>
/// <param><c>o</c> is the object to be compared to the current object.
/// </param>
/// <returns>True if the Points have the same location and they have
/// the exact same type; otherwise, false.</returns>
/// <seealso cref="operator=="/>
/// <seealso cref="operator!="/>
public override bool Equals(object o) {
if (o == null) {
return false;
}

if (this == o) {
return true;
}

if (GetType() == o.GetType()) {
Point p = (Point)o;
return (X == p.X) && (Y == p.Y);
}
return false;
}

/// <summary>Report a point's location as a string.</summary>
/// <returns>A string representing a point's location, in the form (x,y),
/// without any leading, training, or embedded whitespace.</returns>
public override string ToString() {
return "(" + X + "," + Y + ")";
}

/// <summary>This operator determines whether two Points have the same
/// location.</summary>
/// <param><c>p1</c> is the first Point to be compared.</param>
/// <param><c>p2</c> is the second Point to be compared.</param>
/// <returns>True if the Points have the same location and they have
/// the exact same type; otherwise, false.</returns>
/// <seealso cref="Equals"/>
/// <seealso cref="operator!="/>
public static bool operator==(Point p1, Point p2) {
if ((object)p1 == null || (object)p2 == null) {
return false;
}

if (p1.GetType() == p2.GetType()) {
return (p1.X == p2.X) && (p1.Y == p2.Y);
}

return false;
}

/// <summary>This operator determines whether two Points have the same
/// location.</summary>
/// <param><c>p1</c> is the first Point to be compared.</param>
/// <param><c>p2</c> is the second Point to be compared.</param>
/// <returns>True if the Points do not have the same location and the
/// exact same type; otherwise, false.</returns>
/// <seealso cref="Equals"/>
/// <seealso cref="operator=="/>
public static bool operator!=(Point p1, Point p2) {
return !(p1 == p2);
}

/// <summary>This is the entry point of the Point class testing
/// program.
/// <para>This program tests each method and operator, and
/// is intended to be run after any non-trvial maintenance has
/// been performed on the Point class.</para></summary>
public static void Main() {
// class test code goes here
}
}
}

A.4.2 Resulting XML

Here is the output produced by one documentation generator when given the source code for class Point, shown above:

<?xml version="1.0"?>
<doc>
<assembly>
<name>Point</name>
</assembly>
<members>
<member name="T:Graphics.Point">
<summary>Class <c>Point</c> models a point in a two-dimensional
plane.
</summary>
</member>

<member name="F:Graphics.Point.x">
<summary>Instance variable <c>x</c> represents the point's
x-coordinate.</summary>
</member>

<member name="F:Graphics.Point.y">
<summary>Instance variable <c>y</c> represents the point's
y-coordinate.</summary>
</member>

<member name="M:Graphics.Point.#ctor">
<summary>This constructor initializes the new Point to
(0,0).</summary>
</member>

<member name="M:Graphics.Point.#ctor(System.Int32,System.Int32)">
<summary>This constructor initializes the new Point to
(<paramref name="xor"/>,<paramref name="yor"/>).</summary>
<param><c>xor</c> is the new Point's x-coordinate.</param>
<param><c>yor</c> is the new Point's y-coordinate.</param>
</member>

<member name="M:Graphics.Point.Move(System.Int32,System.Int32)">
<summary>This method changes the point's location to
the given coordinates.</summary>
<param><c>xor</c> is the new x-coordinate.</param>
<param><c>yor</c> is the new y-coordinate.</param>
<see cref="M:Graphics.Point.Translate(System.Int32,System.Int32)"/>
</member>

<member
name="M:Graphics.Point.Translate(System.Int32,System.Int32)">
<summary>This method changes the point's location by
the given x- and y-offsets.
<example>For example:
<code>
Point p = new Point(3,5);
p.Translate(-1,3);
</code>
results in <c>p</c>'s having the value (2,8).
</example>
</summary>
<param><c>xor</c> is the relative x-offset.</param>
<param><c>yor</c> is the relative y-offset.</param>
<see cref="M:Graphics.Point.Move(System.Int32,System.Int32)"/>
</member>

<member name="M:Graphics.Point.Equals(System.Object)">
<summary>This method determines whether two Points have the same
location.</summary>
<param><c>o</c> is the object to be compared to the current
object.
</param>
<returns>True if the Points have the same location and they have
the exact same type; otherwise, false.</returns>
<seealso
cref="M:Graphics.Point.op_Equality(Graphics.Point,Graphics.Point)"/>
<seealso
cref="M:Graphics.Point.op_Inequality(Graphics.Point,Graphics.Point)"/>
</member>

<member name="M:Graphics.Point.ToString">
<summary>Report a point's location as a string.</summary>
<returns>A string representing a point's location, in the form
(x,y),
without any leading, training, or embedded whitespace.</returns>
</member>

<member
name="M:Graphics.Point.op_Equality(Graphics.Point,Graphics.Point)">
<summary>This operator determines whether two Points have the
same
location.</summary>
<param><c>p1</c> is the first Point to be compared.</param>
<param><c>p2</c> is the second Point to be compared.</param>
<returns>True if the Points have the same location and they have
the exact same type; otherwise, false.</returns>
<seealso cref="M:Graphics.Point.Equals(System.Object)"/>
<seealso
cref="M:Graphics.Point.op_Inequality(Graphics.Point,Graphics.Point)"/>
</member>

<member
name="M:Graphics.Point.op_Inequality(Graphics.Point,Graphics.Point)">
<summary>This operator determines whether two Points have the
same
location.</summary>
<param><c>p1</c> is the first Point to be compared.</param>
<param><c>p2</c> is the second Point to be compared.</param>
<returns>True if the Points do not have the same location and
the
exact same type; otherwise, false.</returns>
<seealso cref="M:Graphics.Point.Equals(System.Object)"/>
<seealso
cref="M:Graphics.Point.op_Equality(Graphics.Point,Graphics.Point)"/>
</member>

<member name="M:Graphics.Point.Main">
<summary>This is the entry point of the Point class testing
program.
<para>This program tests each method and operator, and
is intended to be run after any non-trvial maintenance has
been performed on the Point class.</para></summary>
</member>

<member name="P:Graphics.Point.X">
<value>Property <c>X</c> represents the point's
x-coordinate.</value>
</member>

<member name="P:Graphics.Point.Y">
<value>Property <c>Y</c> represents the point's
y-coordinate.</value>
</member>
</members>
</doc>


 

B. Grammar

This appendix contains summaries of the lexical and syntactic grammars found in the main document, and of the grammar extensions for unsafe code. Grammar productions appear here in the same order that they appear in the main document.

B.1 Lexical grammar

input:
input-sectionopt

input-section:
input-section-part
input-section input-section-part

input-section-part:
input-elementsopt new-line
pp-directive

input-elements:
input-element
input-elements input-element

input-element:
whitespace
comment
token

B.1.1 Line terminators

new-line:
Carriage return character (U+000D)
Line feed character (U+000A)
Carriage return character (U+000D) followed by line feed character (U+000A)
Next line character(U+0085)
Line separator character (U+2028)
Paragraph separator character (U+2029)

B.1.2 Comments

comment:
single-line-comment
delimited-comment

single-line-comment:
// input-charactersopt

input-characters:
input-character
input-characters input-character

input-character:
Any Unicode character except a new-line-character

new-line-character:
Carriage return character (U+000D)
Line feed character (U+000A)
Next line character(U+0085)
Line separator character (U+2028)
Paragraph separator character (U+2029)

delimited-comment:
/* delimited-comment-textopt asterisks /

delimited-comment-text:
delimited-comment-section
delimited-comment-text delimited-comment-section

delimited-comment-section:
/
asterisksopt not-slash-or-asterisk

asterisks:
*
asterisks *

not-slash-or-asterisk:
Any Unicode character except / or *

B.1.3 White space

whitespace:
Any character with Unicode class Zs
Horizontal tab character (U+0009)
Vertical tab character (U+000B)
Form feed character (U+000C)

B.1.4 Tokens

token:
identifier
keyword
integer-literal
real-literal
character-literal
string-literal
operator-or-punctuator

B.1.5 Unicode character escape sequences

unicode-escape-sequence:
\u hex-digit hex-digit hex-digit hex-digit
\U hex-digit hex-digit hex-digit hex-digit hex-digit hex-digit hex-digit hex-digit

B.1.6 Identifiers

identifier:
available-identifier
@ identifier-or-keyword

available-identifier:
An identifier-or-keyword that is not a keyword

identifier-or-keyword:
identifier-start-character identifier-part-charactersopt

identifier-start-character:
letter-character
_ (the underscore character U+005F)

identifier-part-characters:
identifier-part-character
identifier-part-characters identifier-part-character

identifier-part-character:
letter-character
decimal-digit-character
connecting-character
combining-character
formatting-character

letter-character:
A Unicode character of classes Lu, Ll, Lt, Lm, Lo, or Nl
A unicode-escape-sequence representing a character of classes Lu, Ll, Lt, Lm, Lo, or Nl

combining-character:
A Unicode character of classes Mn or Mc
A unicode-escape-sequence representing a character of classes Mn or Mc

decimal-digit-character:
A Unicode character of the class Nd
A unicode-escape-sequence representing a character of the class Nd

connecting-character:
A Unicode character of the class Pc
A unicode-escape-sequence representing a character of the class Pc

formatting-character:
A Unicode character of the class Cf
A unicode-escape-sequence representing a character of the class Cf

B.1.7 Keywords

keyword: one of
abstract as base bool break
byte case catch char checked
class const continue decimal default
delegate do double else enum
event explicit extern false finally
fixed float for foreach goto
if implicit in int interface
internal is lock long namespace
new null object operator out
override params private protected public
readonly ref return sbyte sealed
short sizeof stackalloc static string
struct switch this throw true
try typeof uint ulong unchecked
unsafe ushort using virtual void
volatile while

B.1.8 Literals

literal:
boolean-literal
integer-literal
real-literal
character-literal
string-literal
null-literal

boolean-literal:
true
false

integer-literal:
decimal-integer-literal
hexadecimal-integer-literal

decimal-integer-literal:
decimal-digits integer-type-suffixopt

decimal-digits:
decimal-digit
decimal-digits decimal-digit

decimal-digit: one of
0 1 2 3 4 5 6 7 8 9

integer-type-suffix: one of
U u L l UL Ul uL ul LU Lu lU lu

hexadecimal-integer-literal:
0x hex-digits integer-type-suffixopt
0X hex-digits integer-type-suffixopt

hex-digits:
hex-digit
hex-digits hex-digit

hex-digit: one of
0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f

real-literal:
decimal-digits . decimal-digits exponent-partopt real-type-suffixopt
. decimal-digits exponent-partopt real-type-suffixopt
decimal-digits exponent-part real-type-suffixopt
decimal-digits real-type-suffix

exponent-part:
e signopt decimal-digits
E signopt decimal-digits

sign: one of
+ -

real-type-suffix: one of
F f D d M m

character-literal:
' character '

character:
single-character
simple-escape-sequence
hexadecimal-escape-sequence
unicode-escape-sequence

single-character:
Any character except ' (U+0027), \ (U+005C), and new-line-character

simple-escape-sequence: one of
\' \" \\ \0 \a \b \f \n \r \t \v

hexadecimal-escape-sequence:
\x hex-digit hex-digitopt hex-digitopt hex-digitopt

string-literal:
regular-string-literal
verbatim-string-literal

regular-string-literal:
" regular-string-literal-charactersopt "

regular-string-literal-characters:
regular-string-literal-character
regular-string-literal-characters regular-string-literal-character

regular-string-literal-character:
single-regular-string-literal-character
simple-escape-sequence
hexadecimal-escape-sequence
unicode-escape-sequence

single-regular-string-literal-character:
Any character except " (U+0022), \ (U+005C), and new-line-character

verbatim-string-literal:
@" verbatim-string-literal-charactersopt "

verbatim-string-literal-characters:
verbatim-string-literal-character
verbatim-string-literal-characters verbatim-string-literal-character

verbatim-string-literal-character:
single-verbatim-string-literal-character
quote-escape-sequence

single-verbatim-string-literal-character:
any character except "

quote-escape-sequence:
""

null-literal:
null

B.1.9 Operators and punctuators

operator-or-punctuator: one of
{ } [ ] ( ) . , : ;
+ - * / % & | ^ ! ~
= < > ? ?? :: ++ -- && ||
-> == != <= >= += -= *= /= %=
&= |= ^= << <<= =>

right-shift:
>|>

right-shift-assignment:
>|>=

B.1.10 Pre-processing directives

pp-directive:
pp-declaration
pp-conditional
pp-line
pp-diagnostic
pp-region
pp-pragma

conditional-symbol:
Any identifier-or-keyword except true or false

pp-expression:
whitespaceopt pp-or-expression whitespaceopt

pp-or-expression:
pp-and-expression
pp-or-expression whitespaceopt || whitespaceopt pp-and-expression

pp-and-expression:
pp-equality-expression
pp-and-expression whitespaceopt && whitespaceopt pp-equality-expression

pp-equality-expression:
pp-unary-expression
pp-equality-expression whitespaceopt == whitespaceopt pp-unary-expression
pp-equality-expression whitespaceopt != whitespaceopt pp-unary-expression

pp-unary-expression:
pp-primary-expression
! whitespaceopt pp-unary-expression

pp-primary-expression:
true
false
conditional-symbol
( whitespaceopt pp-expression whitespaceopt )

pp-declaration:
whitespaceopt # whitespaceopt define whitespace conditional-symbol pp-new-line
whitespaceopt # whitespaceopt undef whitespace conditional-symbol pp-new-line

pp-new-line:
whitespaceopt single-line-commentopt new-line

pp-conditional:
pp-if-section pp-elif-sectionsopt pp-else-sectionopt pp-endif

pp-if-section:
whitespaceopt # whitespaceopt if whitespace pp-expression pp-new-line conditional-sectionopt

pp-elif-sections:
pp-elif-section
pp-elif-sections pp-elif-section

pp-elif-section:
whitespaceopt # whitespaceopt elif whitespace pp-expression pp-new-line conditional-sectionopt

pp-else-section:
whitespaceopt # whitespaceopt else pp-new-line conditional-sectionopt

pp-endif:
whitespaceopt # whitespaceopt endif pp-new-line

conditional-section:
input-section
skipped-section

skipped-section:
skipped-section-part
skipped-section skipped-section-part

skipped-section-part:
skipped-charactersopt new-line
pp-directive

skipped-characters:
whitespaceopt not-number-sign input-charactersopt

not-number-sign:
Any input-character except #

pp-diagnostic:
whitespaceopt # whitespaceopt error pp-message
whitespaceopt # whitespaceopt warning pp-message

pp-message:
new-line
whitespace input-charactersopt new-line

pp-region:
pp-start-region conditional-sectionopt pp-end-region

pp-start-region:
whitespaceopt # whitespaceopt region pp-message

pp-end-region:
whitespaceopt # whitespaceopt endregion pp-message

pp-line:
whitespaceopt # whitespaceopt line whitespace line-indicator pp-new-line

line-indicator:
decimal-digits whitespace file-name
decimal-digits
default
hidden

file-name:
" file-name-characters "

file-name-characters:
file-name-character
file-name-characters file-name-character

file-name-character:
Any input-character except "

pp-pragma:
whitespaceopt # whitespaceopt pragma whitespace pragma-body pp-new-line

pragma-body:
pragma-warning-body





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