Two `Handle[T]` are equal if and only if the values used to produce the
handles are equal, allowing programs to deduplicate values and reduce
their memory footprint.
Comparing two `Handle[T]` values is efficient, reducing down to a simple

# The Go Programming Language

Go is an open source programming language that makes it easy to build simple,
reliable, and efficient software.

![Gopher image](https://golang.org/doc/gopher/fiveyears.jpg)
*Gopher image by [Renee French][rf], licensed under [Creative Commons 4.0 Attributions license][cc4-by].*

Our canonical Git repository is located at https://go.googlesource.com/go.
There is a mirror of the repository at https://github.com/golang/go.

package lex

import (
	"go/build/constraint"
	"io"
	"os"
	"strings"
	"text/scanner"
	"unicode"

	"cmd/asm/internal/flags"
	"cmd/internal/objabi"
	"cmd/internal/src"
)

// A Tokenizer is a simple wrapping of text/scanner.Scanner, configured
// for our purposes and made a TokenReader. It forms the lowest level,
// turning text from readers into tokens.
type Tokenizer struct {
	tok  ScanToken
	s    *scanner.Scanner

	}
	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "shouldn't see an error scanning a string")
	}
	// Output:
	// true
}

// Use a Scanner to implement a simple word-count utility by scanning the
// input as a sequence of space-delimited tokens.
func ExampleScanner_words() {
	// An artificial input source.

}

var (
	D        MultiFlag
	I        MultiFlag
	PrintOut int
	DebugV   bool
)

func init() {
	flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifier=value; can be set multiple times")
	flag.Var(&I, "I", "include directory; can be set multiple times")
	flag.BoolVar(&DebugV, "v", false, "print debug output")

package asm

import (
	"cmd/asm/internal/lex"
	"strings"
	"testing"
	"text/scanner"
)

type exprTest struct {
	input  string
	output int64
	atEOF  bool
}

var exprTests = []exprTest{
	// Simple
	{"0", 0, true},
	{"3", 3, true},
	{"070", 8 * 7, true},
	{"0x0f", 15, true},
	{"0xFF", 255, true},
	{"9223372036854775807", 9223372036854775807, true}, // max int64
	// Unary
	{"-0", 0, true},

The same assembler is used for all target operating systems and architectures.
The GOOS and GOARCH environment variables set the desired target.

Flags:

	-D name[=value]
		Predefine symbol name with an optional simple value.
		Can be repeated to define multiple symbols.
	-I dir1 -I dir2
		Search for #include files in dir1, dir2, etc,
		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	-S
		Print assembly and machine code.
	-V

	"text/scanner"

	"cmd/internal/src"
)

// A ScanToken represents an input item. It is a simple wrapping of rune, as
// returned by text/scanner.Scanner, plus a couple of extra values.
type ScanToken rune

const (
	// Asm defines some two-character lexemes. We make up
	// a rune/ScanToken value for them - ugly but simple.
	LSH          ScanToken = -1000 - iota // << Left shift.

	"text/scanner"
)

type lexTest struct {
	name   string
	input  string
	output string
}

var lexTests = []lexTest{
	{
		"empty",
		"",
		"",
	},
	{
		"simple",
		"1 (a)",
		"1.(.a.)",
	},
	{
		"simple define",
		lines(
			"#define A 1234",
			"A",
		),
		"1234.\n",
	},
	{
		"define without value",
		"#define A",
		"",
	},
	{
		"macro without arguments",