switch {
		case g == nil:
			// No g: we're on a C stack or a signal stack.
			ret = callCgoSigaction(uintptr(sig), new, old)
		case sp < g.stack.lo || sp >= g.stack.hi:
			// We're no longer on g's stack, so we must be handling a signal.  It's
			// possible that we interrupted the thread during a transition between g
			// and g0, so we should stay on the current stack to avoid corrupting g0.
			ret = callCgoSigaction(uintptr(sig), new, old)

GoBlock dt=4 reason_string=12 stack=25
GoStart dt=3 g=19 g_seq=1
GoUnblock dt=5 g=1 g_seq=7 stack=26
GoBlock dt=2 reason_string=15 stack=27
GoStart dt=2 g=1 g_seq=8
GoCreate dt=8 new_g=20 new_stack=23 stack=24
GoBlock dt=3 reason_string=12 stack=25
GoStart dt=2 g=20 g_seq=1
GoUnblock dt=3 g=1 g_seq=9 stack=26
GoBlock dt=1 reason_string=15 stack=27
GoStart dt=2 g=1 g_seq=10

func balancedParentheses(s string) bool {
	var stack []byte
	for _, ch := range s {
		var open byte
		switch ch {
		case '(', '[', '{':
			stack = append(stack, byte(ch))
			continue
		case ')':
			open = '('
		case ']':
			open = '['
		case '}':
			open = '{'
		default:
			continue
		}
		// closing parenthesis/bracket must have matching opening
		top := len(stack) - 1
		if top < 0 || stack[top] != open {

            advanceIfNecessary();
            if (stack.isEmpty()) {
                return endOfData();
            }
            return stack.getLast().next();
        }

        private void advanceIfNecessary() {
            while (!stack.isEmpty() && !hasNextWithCorrectDepth()) {
                if (stack.getLast().hasNext()) {
                    File next = stack.getLast().next();

			pop := ev.index
			stack = append(stack, ev.node)
			if ev.typ&mask != 0 {
				if !f(ev.node, true, stack) {
					i = pop + 1
					stack = stack[:len(stack)-1]
					continue
				}
			}
			if in.events[pop].typ&mask == 0 {
				// Subtrees does not contain types: skip them.
				i = pop
				continue
			}
		} else {
			// pop
			push := ev.index
			if in.events[push].typ&mask != 0 {

        }
        return pop(stack);
      }

      <E extends @Nullable Object> void push(List<E> stack, E value) {
        stack.add(value);
      }

      <E extends @Nullable Object> E pop(List<E> stack) {
        return stack.remove(stack.size() - 1);
      }
    };

    abstract <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>

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

// Input is the main input: a stack of readers and some macro definitions.
// It also handles #include processing (by pushing onto the input stack)
// and parses and instantiates macro definitions.
type Input struct {
	Stack
	includes        []string
	beginningOfLine bool
	ifdefStack      []bool
	macros          map[string]*Macro

	// g here.
	// Also don't save g if we are already on the signal stack.
	// We won't get a nested signal.
	MOVBZ	runtime·iscgo(SB), R22
	CMP	R22, $0
	BNE	nosaveg
	MOVD	m_gsignal(R21), R22	// g.m.gsignal
	CMP	R22, $0
	BEQ	nosaveg

	CMP	g, R22
	BEQ	nosaveg
	MOVD	(g_stack+stack_lo)(R22), R22 // g.m.gsignal.stack.lo
	MOVD	g, (R22)

	BL	(CTR)	// Call from VDSO

// alternate signal stack. If the alternate signal stack is not set
// for the thread (the normal case) then set the alternate signal
// stack to the gsignal stack. If the alternate signal stack is set
// for the thread (the case when a non-Go thread sets the alternate
// signal stack and then calls a Go function) then set the gsignal
// stack to the alternate signal stack. We also set the alternate

// license that can be found in the LICENSE file.

// Trace stack table and acquisition.

package runtime

import (
	"internal/abi"
	"internal/goarch"
	"unsafe"
)

const (
	// Maximum number of PCs in a single stack trace.
	// Since events contain only stack id rather than whole stack trace,
	// we can allow quite large values here.
	traceStackSize = 128