chromedp/context.go
Daniel Martí 0d568ec2a4 change Run to allow many actions
This can simplify some common use cases, like running a few actions
directly, or running no actions at all. It's also an almost entirely
backwards compatible change, as all Run call sites should continue to
compile and work.

Leave Tasks, as it can still be useful for functions to return complex
sequences of actions as a single Action.
2019-04-01 16:59:23 +01:00

116 lines
2.6 KiB
Go

package chromedp
import (
"context"
"fmt"
"github.com/chromedp/cdproto/css"
"github.com/chromedp/cdproto/dom"
"github.com/chromedp/cdproto/inspector"
"github.com/chromedp/cdproto/log"
"github.com/chromedp/cdproto/page"
"github.com/chromedp/cdproto/runtime"
"github.com/chromedp/cdproto/target"
)
// Context is attached to any context.Context which is valid for use with Run.
type Context struct {
Allocator Allocator
Browser *Browser
Target *Target
}
// NewContext creates a browser context using the parent context.
func NewContext(parent context.Context, opts ...ContextOption) (context.Context, context.CancelFunc) {
ctx, cancel := context.WithCancel(parent)
c := &Context{}
if pc := FromContext(parent); pc != nil {
c.Allocator = pc.Allocator
c.Browser = pc.Browser
// don't inherit SessionID, so that NewContext can be used to
// create a new tab on the same browser.
}
for _, o := range opts {
o(c)
}
if c.Allocator == nil {
WithExecAllocator(
NoFirstRun,
NoDefaultBrowserCheck,
Headless,
)(&c.Allocator)
}
ctx = context.WithValue(ctx, contextKey{}, c)
return ctx, cancel
}
type contextKey struct{}
// FromContext extracts the Context data stored inside a context.Context.
func FromContext(ctx context.Context) *Context {
c, _ := ctx.Value(contextKey{}).(*Context)
return c
}
// Run runs an action against the provided context. The provided context must
// contain a valid Allocator; typically, that will be created via NewContext or
// NewAllocator.
func Run(ctx context.Context, actions ...Action) error {
c := FromContext(ctx)
if c == nil || c.Allocator == nil {
return ErrInvalidContext
}
if c.Browser == nil {
browser, err := c.Allocator.Allocate(ctx)
if err != nil {
return err
}
c.Browser = browser
}
if c.Target == nil {
if err := c.newSession(ctx); err != nil {
return err
}
}
return Tasks(actions).Do(ctx, c.Target)
}
func (c *Context) newSession(ctx context.Context) error {
create := target.CreateTarget("about:blank")
targetID, err := create.Do(ctx, c.Browser)
if err != nil {
return err
}
attach := target.AttachToTarget(targetID)
sessionID, err := attach.Do(ctx, c.Browser)
if err != nil {
return err
}
c.Target = c.Browser.newExecutorForTarget(ctx, sessionID)
// enable domains
for _, enable := range []Action{
log.Enable(),
runtime.Enable(),
//network.Enable(),
inspector.Enable(),
page.Enable(),
dom.Enable(),
css.Enable(),
} {
if err := enable.Do(ctx, c.Target); err != nil {
return fmt.Errorf("unable to execute %T: %v", enable, err)
}
}
return nil
}
type ContextOption func(*Context)