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-rw-r--r--lib/ui/context.go8
-rw-r--r--lib/ui/stack.go4
-rw-r--r--lib/ui/text.go2
3 files changed, 7 insertions, 7 deletions
diff --git a/lib/ui/context.go b/lib/ui/context.go
index 1665819..d7796bf 100644
--- a/lib/ui/context.go
+++ b/lib/ui/context.go
@@ -3,9 +3,9 @@ package ui
 import (
 	"fmt"
 
-	"github.com/mattn/go-runewidth"
 	"github.com/gdamore/tcell"
 	"github.com/gdamore/tcell/views"
+	"github.com/mattn/go-runewidth"
 )
 
 // A context allows you to draw in a sub-region of the terminal
@@ -40,10 +40,10 @@ func NewContext(width, height int, screen tcell.Screen) *Context {
 
 func (ctx *Context) Subcontext(x, y, width, height int) *Context {
 	vp_width, vp_height := ctx.viewport.Size()
-	if (x < 0 || y < 0) {
+	if x < 0 || y < 0 {
 		panic(fmt.Errorf("Attempted to create context with negative offset"))
 	}
-	if (x + width > vp_width || y + height > vp_height) {
+	if x+width > vp_width || y+height > vp_height {
 		panic(fmt.Errorf("Attempted to create context larger than parent"))
 	}
 	vp := views.NewViewPort(ctx.viewport, x, y, width, height)
@@ -88,7 +88,7 @@ func (ctx *Context) Printf(x, y int, style tcell.Style,
 			crunes := []rune{}
 			ctx.viewport.SetContent(x, y, ch, crunes, style)
 			x += runewidth.RuneWidth(ch)
-			if x == old_x + width {
+			if x == old_x+width {
 				if !newline() {
 					return runewidth.StringWidth(str)
 				}
diff --git a/lib/ui/stack.go b/lib/ui/stack.go
index 2b97e78..2e3f0b9 100644
--- a/lib/ui/stack.go
+++ b/lib/ui/stack.go
@@ -7,7 +7,7 @@ import (
 )
 
 type Stack struct {
-	children []Drawable
+	children     []Drawable
 	onInvalidate []func(d Drawable)
 }
 
@@ -15,7 +15,7 @@ func NewStack() *Stack {
 	return &Stack{}
 }
 
-func (stack *Stack) OnInvalidate(onInvalidate func (d Drawable)) {
+func (stack *Stack) OnInvalidate(onInvalidate func(d Drawable)) {
 	stack.onInvalidate = append(stack.onInvalidate, onInvalidate)
 }
 
diff --git a/lib/ui/text.go b/lib/ui/text.go
index e2e218c..d3f6c6b 100644
--- a/lib/ui/text.go
+++ b/lib/ui/text.go
@@ -1,8 +1,8 @@
 package ui
 
 import (
-	"github.com/mattn/go-runewidth"
 	"github.com/gdamore/tcell"
+	"github.com/mattn/go-runewidth"
 )
 
 const (
{ color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; } span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; } .highlight .hll { background-color: #ffffcc } .highlight .c { color: #888888 } /* Comment */ .highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */ .highlight .k { color: #008800; font-weight: bold } /* Keyword */ .highlight .ch { color: #888888 } /* Comment.Hashbang */ .highlight .cm { color: #888888 } /* Comment.Multiline */ .highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */ .highlight .cpf { color: #888888 } /* Comment.PreprocFile */ .highlight .c1 { color: #888888 } /* Comment.Single */ .highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */ .highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */ .highlight .ge { font-style: italic } /* Generic.Emph */ .highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */ .highlight .gr { color: #aa0000 } /* Generic.Error */ .highlight .gh { color: #333333 } /* Generic.Heading */ .highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */ .highlight .go { color: #888888 } /* Generic.Output */ .highlight .gp { color: #555555 } /* Generic.Prompt */ .highlight .gs { font-weight: bold } /* Generic.Strong */ .highlight .gu { color: #666666 } /* Generic.Subheading */ .highlight .gt { color: #aa0000 } /* Generic.Traceback */ .highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */ .highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */ .highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */ .highlight .kp { color: #008800 } /* Keyword.Pseudo */ .highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */ .highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */ .highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */ .highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */ .highlight .na { color: #336699 } /* Name.Attribute */ .highlight .nb { color: #003388 } /* Name.Builtin */ .highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */ .highlight .no { color: #003366; font-weight: bold } /* Name.Constant */ .highlight .nd { color: #555555 } /* Name.Decorator */ .highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */ .highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */ .highlight .nl { color: #336699; font-style: italic } /* Name.Label */ .highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */ .highlight .py { color: #336699; font-weight: bold } /* Name.Property */ .highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */ .highlight .nv { color: #336699 } /* Name.Variable */ .highlight .ow { color: #008800 } /* Operator.Word */ .highlight .w { color: #bbbbbb } /* Text.Whitespace */ .highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */ .highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */ .highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */ .highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */ .highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */ .highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */ .highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */ .highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */ .highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */ .highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */ .highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */ .highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */ .highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */ .highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */ .highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */ .highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */ .highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */ .highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */ .highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */ .highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */ .highlight .vc { color: #336699 } /* Name.Variable.Class */ .highlight .vg { color: #dd7700 } /* Name.Variable.Global */ .highlight .vi { color: #3333bb } /* Name.Variable.Instance */ .highlight .vm { color: #336699 } /* Name.Variable.Magic */ .highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
# stop: dependency-injected wrapper around the exit() syscall
#
# We'd like to be able to write tests for functions that call exit(), and to
# make assertions about whether they exit() or not in a given situation. To
# achieve this we'll call exit() via a smarter wrapper called 'stop'.
#
# In the context of a test, calling a function X that calls 'stop' (directly
# or through further intervening calls) will unwind the stack until X returns,
# so that we can say check any further assertions after the execution of X. To
# achieve this end, we'll pass the return address of X as a 'target' argument
# into X, plumbing it through to 'stop'. When 'stop' gets a non-null target it
# unwinds the stack until the target. If it gets a null target it calls
# exit().
#
# We'd also like to get the exit status out of 'stop', so we'll combine the
# input target with an output status parameter into a type called 'exit-descriptor'.
#
# So the exit-descriptor looks like this:
#   target : address  # return address for 'stop' to unwind to
#   value : int  # exit status stop was called with
#
# 'stop' thus takes two parameters: an exit-descriptor and the exit status.
#
# 'stop' won't bother cleaning up any other processor state besides the stack,
# such as registers. Only esp will have a well-defined value after 'stop'
# returns. (This is a poor man's setjmp/longjmp, if you know what that is.)
#
# Before you can call any function that may call 'stop', you need to pass in an
# exit-descriptor to it. To create an exit-descriptor use 'tailor-exit-descriptor'
# below. It's not the most pleasant abstraction in the world.
#
# An exit-descriptor's target is its input, computed during 'tailor-exit-descriptor'.
# Its value is its output, computed during stop and available to the test.

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

# Configure an exit-descriptor for a call pushing 'nbytes' bytes of args to
# the stack.
# Ugly that we need to know the size of args. Don't allocate variables between
# tailor-exit-descriptor and the call it's for.
tailor-exit-descriptor:  # ed : (address exit-descriptor), nbytes : int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    # eax = nbytes
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   0xc/disp8       .                 # copy *(ebp+12) to eax
    # Let X be the value of esp in the caller, before the call to tailor-exit-descriptor.
    # The return address for a call in the caller's body will be at:
    #   X-8 if the caller takes 4 bytes of args for the exit-descriptor (add 4 bytes for the return address)
    #   X-12 if the caller takes 8 bytes of args
    #   ..and so on
    # That's the value we need to return: X-nbytes-4
    #
    # However, we also need to account for the perturbance to esp caused by the
    # call to tailor-exit-descriptor. It pushes 8 bytes of args followed by 4
    # bytes for the return address and 4 bytes to push ebp above.
    # So ebp at this point is X-16.
    #
    # So the return address for the next call in the caller is:
    #   ebp+8 if the caller takes 4 bytes of args
    #   ebp+4 if the caller takes 8 bytes of args
    #   ebp if the caller takes 12 bytes of args
    #   ebp-4 if the caller takes 16 bytes of args
    #   ..and so on
    # That's ebp+12-nbytes.
    # option 1: 6 + 3 bytes
#?     2d/subtract                     3/mod/direct    0/rm32/eax    .           .             .           .           .               8/imm32           # subtract from eax
#?     8d/copy-address                 0/mod/indirect  4/rm32/sib    5/base/ebp  0/index/eax   .           0/r32/eax   .               .                 # copy ebp+eax to eax
    # option 2: 2 + 4 bytes
    f7          3/subop/negate      3/mod/direct    0/rm32/eax    .           .             .           .           .               .                 # negate eax
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    5/base/ebp  0/index/eax   .           0/r32/eax   0xc/disp8         .               # copy ebp+eax+12 to eax
    # copy eax to ed->target
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    89/copy                         0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # copy eax to *ecx
    # initialize ed->value
    c7          0/subop/copy        1/mod/*+disp8   1/rm32/ecx    .           .             .           .           4/disp8         0/imm32           # copy to *(ecx+4)
$tailor-exit-descriptor:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

stop:  # ed : (address exit-descriptor), value : int
    # no prologue; one way or another, we're going to clobber registers
    # eax = ed
    8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/esp  4/index/none  .           0/r32/eax   4/disp8         .                 # copy *(esp+4) to eax
    # if (ed->target == 0) really exit
    81          7/subop/compare     0/mod/indirect  0/rm32/eax    .           .             .           .           .               0/imm32           # compare *eax
    75/jump-if-not-equal  $stop:fake/disp8
    # . syscall(exit, value)
    8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/esp  4/index/none  .           3/r32/ebx   8/disp8         .                 # copy *(esp+8) to ebx
    b8/copy-to-eax  1/imm32/exit
    cd/syscall  0x80/imm8
$stop:fake:
    # otherwise:
    # ed->value = value+1
    8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/esp  4/index/none  .           1/r32/ecx   8/disp8         .                 # copy *(esp+8) to ecx
    41/increment-ecx
    89/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           1/r32/ecx   4/disp8         .                 # copy ecx to *(eax+4)
    # perform a non-local jump to ed->target
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           4/r32/esp   .               .                 # copy *eax to esp
$stop:end:
    c3/return  # doesn't return to caller

test-stop-skips-returns-on-exit:
    # This looks like the standard prologue, but is here for different reasons.
    # A function calling 'stop' can't rely on ebp persisting past the call.
    #
    # Use ebp here as a stable base to refer to locals and arguments from in the
    # presence of push/pop/call instructions.
    # *Don't* use ebp as a way to restore esp.
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # Make room for an exit descriptor on the stack. That's almost always the
    # right place for it, available only as long as it's legal to use. Once this
    # containing function returns we'll need a new exit descriptor.
    # var ed/eax : (ref exit-descriptor)
    68/push  0/imm32
    68/push  0/imm32
    89/copy                         3/mod/direct    0/rm32/eax    .           .             .           4/r32/esp   .               .                 # copy esp to eax
    # Size the exit-descriptor precisely for the next call below, to _test-stop-1.
    # tailor-exit-descriptor(ed, 4)
    # . . push args
    68/push  4/imm32/nbytes-of-args-for-_test-stop-1
    50/push-eax
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # . _test-stop-1(ed)
    # . . push args
    50/push-eax
    # . . call
    e8/call  _test-stop-1/disp32
    # registers except esp may be clobbered at this point
    # restore args
    58/pop-to-eax
    # check that _test-stop-1 tried to call exit(1)
    # . check-ints-equal(ed->value, 2, msg)  # i.e. stop was called with value 1
    # . . push args
    68/push  "F - test-stop-skips-returns-on-exit"/imm32
    68/push  2/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         .                 # push *(eax+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    # don't restore esp from ebp; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    5d/pop-to-ebp
    c3/return

_test-stop-1:  # ed : (address exit-descriptor)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # _test-stop-2(ed)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
    # . . call
    e8/call  _test-stop-2/disp32
    # should never get past this point
$_test-stop-1:dead-end:
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # signal test failed: check-ints-equal(1, 0, msg)
    # . . push args
    68/push  "F - test-stop-skips-returns-on-exit"/imm32
    68/push  0/imm32
    68/push  1/imm32
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

_test-stop-2:  # ed : (address exit-descriptor)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . stop(ed, 1)
    # . . push args
    68/push  1/imm32
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
    # . . call
    e8/call  stop/disp32
    # should never get past this point
$_test-stop-2:dead-end:
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# . . vim:nowrap:textwidth=0