func (p *Parser) line(scratch [][]lex.Token) (word, cond string, operands [][]lex.Token, ok bool) {
next:
	// Skip newlines.
	var tok lex.ScanToken
	for {
		tok = p.nextToken()
		// We save the line number here so error messages from this instruction
		// are labeled with this line. Otherwise we complain after we've absorbed
		// the terminating newline and the line numbers are off by one in errors.
		p.lineNum = p.lex.Line()
		switch tok {

	for _, f := range strings.Split(s, " or ") {
		if f == "" || len(f)%2 != 0 || strings.TrimLeft(f, "0123456789abcdef") != "" {
			return false
		}
	}
	return true
}

// It would be nice if the error messages always began with
// the standard file:line: prefix,
// but that's not where we are today.
// It might be at the beginning but it might be in the middle of the printed instruction.

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package flags implements top-level flags and the usage message for the assembler.
package flags

import (
	"cmd/internal/obj"
	"cmd/internal/objabi"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

var (

Cgo takes a different approach. It determines the meaning of C
identifiers not by parsing C code but by feeding carefully constructed
programs into the system C compiler and interpreting the generated
error messages, debug information, and object files. In practice,
parsing these is significantly less work and more robust than parsing
C source.

Cgo first invokes gcc -E -dM on the preamble, in order to find out

		return needType
	}

	// Coerce gcc into telling us whether each name is a type, a value, or undeclared.
	// For names, find out whether they are integer constants.
	// We used to look at specific warning or error messages here, but that tied the
	// behavior too closely to specific versions of the compilers.
	// Instead, arrange that we can infer what we need from only the presence or absence
	// of an error on a specific line.
	//

}

var (
	swigOnce sync.Once
	haveSwig bool
)

func mustHaveSwig(t *testing.T) {
	swigOnce.Do(func() {
		mustHaveSwigOnce(t)
		haveSwig = true
	})
	// The first call will skip t with a nice message. On later calls, we just skip.
	if !haveSwig {
		t.Skip("swig not found")
	}
}

func mustHaveSwigOnce(t *testing.T) {
	swig, err := exec.LookPath("swig")
	if err != nil {
		t.Skipf("swig not in PATH: %s", err)

limits the impact of these use-after-free bugs by preventing reuse of freed
memory regions until the garbage collector is able to determine that it is
safe. Typically, a use-after-free bug will result in a fault and a helpful
error message, but this package reserves the right to not force a fault on
freed memory. That means a valid implementation of this package is to just
allocate all memory the way the runtime normally would, and in fact, it