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// Copyright 2009 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.
// This file implements printing of AST nodes; specifically
// expressions, statements, declarations, and files. It uses
// the print functionality implemented in printer.go.
package printer
import (
"bytes"
"go/ast"
"go/token"
"math"
"strconv"
"strings"
"unicode"
"unicode/utf8"
)
// Formatting issues:
// - better comment formatting for /*-style comments at the end of a line (e.g. a declaration)
// when the comment spans multiple lines; if such a comment is just two lines, formatting is
// not idempotent
// - formatting of expression lists
// - should use blank instead of tab to separate one-line function bodies from
// the function header unless there is a group of consecutive one-liners
// ----------------------------------------------------------------------------
// Common AST nodes.
// Print as many newlines as necessary (but at least min newlines) to get to
// the current line. ws is printed before the first line break. If newSection
// is set, the first line break is printed as formfeed. Returns 0 if no line
// breaks were printed, returns 1 if there was exactly one newline printed,
// and returns a value > 1 if there was a formfeed or more than one newline
// printed.
//
// TODO(gri): linebreak may add too many lines if the next statement at "line"
// is preceded by comments because the computation of n assumes
// the current position before the comment and the target position
// after the comment. Thus, after interspersing such comments, the
// space taken up by them is not considered to reduce the number of
// linebreaks. At the moment there is no easy way to know about
// future (not yet interspersed) comments in this function.
func (p *printer) linebreak(line, min int, ws whiteSpace, newSection bool) (nbreaks int) {
n := nlimit(line - p.pos.Line)
if n < min {
n = min
}
if n > 0 {
p.print(ws)
if newSection {
p.print(formfeed)
n--
nbreaks = 2
}
nbreaks += n
for ; n > 0; n-- {
p.print(newline)
}
}
return
}
// setComment sets g as the next comment if g != nil and if node comments
// are enabled - this mode is used when printing source code fragments such
// as exports only. It assumes that there is no pending comment in p.comments
// and at most one pending comment in the p.comment cache.
func (p *printer) setComment(g *ast.CommentGroup) {
if g == nil || !p.useNodeComments {
return
}
if p.comments == nil {
// initialize p.comments lazily
p.comments = make([]*ast.CommentGroup, 1)
} else if p.cindex < len(p.comments) {
// for some reason there are pending comments; this
// should never happen - handle gracefully and flush
// all comments up to g, ignore anything after that
p.flush(p.posFor(g.List[0].Pos()), token.ILLEGAL)
p.comments = p.comments[0:1]
// in debug mode, report error
p.internalError("setComment found pending comments")
}
p.comments[0] = g
p.cindex = 0
// don't overwrite any pending comment in the p.comment cache
// (there may be a pending comment when a line comment is
// immediately followed by a lead comment with no other
// tokens between)
if p.commentOffset == infinity {
p.nextComment() // get comment ready for use
}
}
type exprListMode uint
const (
commaTerm exprListMode = 1 << iota // list is optionally terminated by a comma
noIndent // no extra indentation in multi-line lists
)
// If indent is set, a multi-line identifier list is indented after the
// first linebreak encountered.
func (p *printer) identList(list []*ast.Ident, indent bool) {
// convert into an expression list so we can re-use exprList formatting
xlist := make([]ast.Expr, len(list))
for i, x := range list {
xlist[i] = x
}
var mode exprListMode
if !indent {
mode = noIndent
}
p.exprList(token.NoPos, xlist, 1, mode, token.NoPos, false)
}
const filteredMsg = "contains filtered or unexported fields"
// Print a list of expressions. If the list spans multiple
// source lines, the original line breaks are respected between
// expressions.
//
// TODO(gri) Consider rewriting this to be independent of []ast.Expr
// so that we can use the algorithm for any kind of list
//
// (e.g., pass list via a channel over which to range).
func (p *printer) exprList(prev0 token.Pos, list []ast.Expr, depth int, mode exprListMode, next0 token.Pos, isIncomplete bool) {
if len(list) == 0 {
if isIncomplete {
prev := p.posFor(prev0)
next := p.posFor(next0)
if prev.IsValid() && prev.Line == next.Line {
p.print("/* " + filteredMsg + " */")
} else {
p.print(newline)
p.print(indent, "// "+filteredMsg, unindent, newline)
}
}
return
}
prev := p.posFor(prev0)
next := p.posFor(next0)
line := p.lineFor(list[0].Pos())
endLine := p.lineFor(list[len(list)-1].End())
if prev.IsValid() && prev.Line == line && line == endLine {
// all list entries on a single line
for i, x := range list {
if i > 0 {
// use position of expression following the comma as
// comma position for correct comment placement
p.print(x.Pos(), token.COMMA, blank)
}
p.expr0(x, depth)
}
if isIncomplete {
p.print(token.COMMA, blank, "/* "+filteredMsg+" */")
}
return
}
// list entries span multiple lines;
// use source code positions to guide line breaks
// Don't add extra indentation if noIndent is set;
// i.e., pretend that the first line is already indented.
ws := ignore
if mode&noIndent == 0 {
ws = indent
}
// The first linebreak is always a formfeed since this section must not
// depend on any previous formatting.
prevBreak := -1 // index of last expression that was followed by a linebreak
if prev.IsValid() && prev.Line < line && p.linebreak(line, 0, ws, true) > 0 {
ws = ignore
prevBreak = 0
}
// initialize expression/key size: a zero value indicates expr/key doesn't fit on a single line
size := 0
// We use the ratio between the geometric mean of the previous key sizes and
// the current size to determine if there should be a break in the alignment.
// To compute the geometric mean we accumulate the ln(size) values (lnsum)
// and the number of sizes included (count).
lnsum := 0.0
count := 0
// print all list elements
prevLine := prev.Line
for i, x := range list {
line = p.lineFor(x.Pos())
// Determine if the next linebreak, if any, needs to use formfeed:
// in general, use the entire node size to make the decision; for
// key:value expressions, use the key size.
// TODO(gri) for a better result, should probably incorporate both
// the key and the node size into the decision process
useFF := true
// Determine element size: All bets are off if we don't have
// position information for the previous and next token (likely
// generated code - simply ignore the size in this case by setting
// it to 0).
prevSize := size
const infinity = 1e6 // larger than any source line
size = p.nodeSize(x, infinity)
pair, isPair := x.(*ast.KeyValueExpr)
if size <= infinity && prev.IsValid() && next.IsValid() {
// x fits on a single line
if isPair {
size = p.nodeSize(pair.Key, infinity) // size <= infinity
}
} else {
// size too large or we don't have good layout information
size = 0
}
// If the previous line and the current line had single-
// line-expressions and the key sizes are small or the
// ratio between the current key and the geometric mean
// if the previous key sizes does not exceed a threshold,
// align columns and do not use formfeed.
if prevSize > 0 && size > 0 {
const smallSize = 40
if count == 0 || prevSize <= smallSize && size <= smallSize {
useFF = false
} else {
const r = 2.5 // threshold
geomean := math.Exp(lnsum / float64(count)) // count > 0
ratio := float64(size) / geomean
useFF = r*ratio <= 1 || r <= ratio
}
}
needsLinebreak := 0 < prevLine && prevLine < line
if i > 0 {
// Use position of expression following the comma as
// comma position for correct comment placement, but
// only if the expression is on the same line.
if !needsLinebreak {
p.print(x.Pos())
}
p.print(token.COMMA)
needsBlank := true
if needsLinebreak {
// Lines are broken using newlines so comments remain aligned
// unless useFF is set or there are multiple expressions on
// the same line in which case formfeed is used.
nbreaks := p.linebreak(line, 0, ws, useFF || prevBreak+1 < i)
if nbreaks > 0 {
ws = ignore
prevBreak = i
needsBlank = false // we got a line break instead
}
// If there was a new section or more than one new line
// (which means that the tabwriter will implicitly break
// the section), reset the geomean variables since we are
// starting a new group of elements with the next element.
if nbreaks > 1 {
lnsum = 0
count = 0
}
}
if needsBlank {
p.print(blank)
}
}
if len(list) > 1 && isPair && size > 0 && needsLinebreak {
// We have a key:value expression that fits onto one line
// and it's not on the same line as the prior expression:
// Use a column for the key such that consecutive entries
// can align if possible.
// (needsLinebreak is set if we started a new line before)
p.expr(pair.Key)
p.print(pair.Colon, token.COLON, vtab)
p.expr(pair.Value)
} else {
p.expr0(x, depth)
}
if size > 0 {
lnsum += math.Log(float64(size))
count++
}
prevLine = line
}
if mode&commaTerm != 0 && next.IsValid() && p.pos.Line < next.Line {
// Print a terminating comma if the next token is on a new line.
p.print(token.COMMA)
if isIncomplete {
p.print(newline)
p.print("// " + filteredMsg)
}
if ws == ignore && mode&noIndent == 0 {
// unindent if we indented
p.print(unindent)
}
p.print(formfeed) // terminating comma needs a line break to look good
return
}
if isIncomplete {
p.print(token.COMMA, newline)
p.print("// "+filteredMsg, newline)
}
if ws == ignore && mode&noIndent == 0 {
// unindent if we indented
p.print(unindent)
}
}
type paramMode int
const (
funcParam paramMode = iota
funcTParam
typeTParam
)
func (p *printer) parameters(fields *ast.FieldList, mode paramMode) {
openTok, closeTok := token.LPAREN, token.RPAREN
if mode != funcParam {
openTok, closeTok = token.LBRACK, token.RBRACK
}
p.print(fields.Opening, openTok)
if len(fields.List) > 0 {
prevLine := p.lineFor(fields.Opening)
ws := indent
for i, par := range fields.List {
// determine par begin and end line (may be different
// if there are multiple parameter names for this par
// or the type is on a separate line)
parLineBeg := p.lineFor(par.Pos())
parLineEnd := p.lineFor(par.End())
// separating "," if needed
needsLinebreak := 0 < prevLine && prevLine < parLineBeg
if i > 0 {
// use position of parameter following the comma as
// comma position for correct comma placement, but
// only if the next parameter is on the same line
if !needsLinebreak {
p.print(par.Pos())
}
p.print(token.COMMA)
}
// separator if needed (linebreak or blank)
if needsLinebreak && p.linebreak(parLineBeg, 0, ws, true) > 0 {
// break line if the opening "(" or previous parameter ended on a different line
ws = ignore
} else if i > 0 {
p.print(blank)
}
// parameter names
if len(par.Names) > 0 {
// Very subtle: If we indented before (ws == ignore), identList
// won't indent again. If we didn't (ws == indent), identList will
// indent if the identList spans multiple lines, and it will outdent
// again at the end (and still ws == indent). Thus, a subsequent indent
// by a linebreak call after a type, or in the next multi-line identList
// will do the right thing.
p.identList(par.Names, ws == indent)
p.print(blank)
}
// parameter type
p.expr(stripParensAlways(par.Type))
prevLine = parLineEnd
}
// if the closing ")" is on a separate line from the last parameter,
// print an additional "," and line break
if closing := p.lineFor(fields.Closing); 0 < prevLine && prevLine < closing {
p.print(token.COMMA)
p.linebreak(closing, 0, ignore, true)
} else if mode == typeTParam && fields.NumFields() == 1 {
// Otherwise, if we are in a type parameter list that could be confused
// with the constant array length expression [P*C], print a comma so that
// parsing is unambiguous.
//
// Note that while ParenExprs can also be ambiguous (issue #49482), the
// printed type is never parenthesized (stripParensAlways is used above).
if t, _ := fields.List[0].Type.(*ast.StarExpr); t != nil && !isTypeLit(t.X) {
p.print(token.COMMA)
}
}
// unindent if we indented
if ws == ignore {
p.print(unindent)
}
}
p.print(fields.Closing, closeTok)
}
// isTypeLit reports whether x is a (possibly parenthesized) type literal.
func isTypeLit(x ast.Expr) bool {
switch x := x.(type) {
case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
return true
case *ast.StarExpr:
// *T may be a pointer dereferenciation.
// Only consider *T as type literal if T is a type literal.
return isTypeLit(x.X)
case *ast.ParenExpr:
return isTypeLit(x.X)
}
return false
}
func (p *printer) signature(sig *ast.FuncType) {
if sig.TypeParams != nil {
p.parameters(sig.TypeParams, funcTParam)
}
if sig.Params != nil {
p.parameters(sig.Params, funcParam)
} else {
p.print(token.LPAREN, token.RPAREN)
}
res := sig.Results
n := res.NumFields()
if n > 0 {
// res != nil
p.print(blank)
if n == 1 && res.List[0].Names == nil {
// single anonymous res; no ()'s
p.expr(stripParensAlways(res.List[0].Type))
return
}
p.parameters(res, funcParam)
}
}
func identListSize(list []*ast.Ident, maxSize int) (size int) {
for i, x := range list {
if i > 0 {
size += len(", ")
}
size += utf8.RuneCountInString(x.Name)
if size >= maxSize {
break
}
}
return
}
func (p *printer) isOneLineFieldList(list []*ast.Field) bool {
if len(list) != 1 {
return false // allow only one field
}
f := list[0]
if f.Tag != nil || f.Comment != nil {
return false // don't allow tags or comments
}
// only name(s) and type
const maxSize = 30 // adjust as appropriate, this is an approximate value
namesSize := identListSize(f.Names, maxSize)
if namesSize > 0 {
namesSize = 1 // blank between names and types
}
typeSize := p.nodeSize(f.Type, maxSize)
return namesSize+typeSize <= maxSize
}
func (p *printer) setLineComment(text string) {
p.setComment(&ast.CommentGroup{List: []*ast.Comment{{Slash: token.NoPos, Text: text}}})
}
func (p *printer) fieldList(fields *ast.FieldList, isStruct, isIncomplete bool) {
lbrace := fields.Opening
list := fields.List
rbrace := fields.Closing
hasComments := isIncomplete || p.commentBefore(p.posFor(rbrace))
srcIsOneLine := lbrace.IsValid() && rbrace.IsValid() && p.lineFor(lbrace) == p.lineFor(rbrace)
if !hasComments && srcIsOneLine {
// possibly a one-line struct/interface
if len(list) == 0 {
// no blank between keyword and {} in this case
p.print(lbrace, token.LBRACE, rbrace, token.RBRACE)
return
} else if p.isOneLineFieldList(list) {
// small enough - print on one line
// (don't use identList and ignore source line breaks)
p.print(lbrace, token.LBRACE, blank)
f := list[0]
if isStruct {
for i, x := range f.Names {
if i > 0 {
// no comments so no need for comma position
p.print(token.COMMA, blank)
}
p.expr(x)
}
if len(f.Names) > 0 {
p.print(blank)
}
p.expr(f.Type)
} else { // interface
if len(f.Names) > 0 {
name := f.Names[0] // method name
p.expr(name)
p.signature(f.Type.(*ast.FuncType)) // don't print "func"
} else {
// embedded interface
p.expr(f.Type)
}
}
p.print(blank, rbrace, token.RBRACE)
return
}
}
// hasComments || !srcIsOneLine
p.print(blank, lbrace, token.LBRACE, indent)
if hasComments || len(list) > 0 {
p.print(formfeed)
}
if isStruct {
sep := vtab
if len(list) == 1 {
sep = blank
}
var line int
for i, f := range list {
if i > 0 {
p.linebreak(p.lineFor(f.Pos()), 1, ignore, p.linesFrom(line) > 0)
}
extraTabs := 0
p.setComment(f.Doc)
p.recordLine(&line)
if len(f.Names) > 0 {
// named fields
p.identList(f.Names, false)
p.print(sep)
p.expr(f.Type)
extraTabs = 1
} else {
// anonymous field
p.expr(f.Type)
extraTabs = 2
}
if f.Tag != nil {
if len(f.Names) > 0 && sep == vtab {
p.print(sep)
}
p.print(sep)
p.expr(f.Tag)
extraTabs = 0
}
if f.Comment != nil {
for ; extraTabs > 0; extraTabs-- {
p.print(sep)
}
p.setComment(f.Comment)
}
}
if isIncomplete {
if len(list) > 0 {
p.print(formfeed)
}
p.flush(p.posFor(rbrace), token.RBRACE) // make sure we don't lose the last line comment
p.setLineComment("// " + filteredMsg)
}
} else { // interface
var line int
var prev *ast.Ident // previous "type" identifier
for i, f := range list {
var name *ast.Ident // first name, or nil
if len(f.Names) > 0 {
name = f.Names[0]
}
if i > 0 {
// don't do a line break (min == 0) if we are printing a list of types
// TODO(gri) this doesn't work quite right if the list of types is
// spread across multiple lines
min := 1
if prev != nil && name == prev {
min = 0
}
p.linebreak(p.lineFor(f.Pos()), min, ignore, p.linesFrom(line) > 0)
}
p.setComment(f.Doc)
p.recordLine(&line)
if name != nil {
// method
p.expr(name)
p.signature(f.Type.(*ast.FuncType)) // don't print "func"
prev = nil
} else {
// embedded interface
p.expr(f.Type)
prev = nil
}
p.setComment(f.Comment)
}
if isIncomplete {
if len(list) > 0 {
p.print(formfeed)
}
p.flush(p.posFor(rbrace), token.RBRACE) // make sure we don't lose the last line comment
p.setLineComment("// contains filtered or unexported methods")
}
}
p.print(unindent, formfeed, rbrace, token.RBRACE)
}
// ----------------------------------------------------------------------------
// Expressions
func walkBinary(e *ast.BinaryExpr) (has4, has5 bool, maxProblem int) {
switch e.Op.Precedence() {
case 4:
has4 = true
case 5:
has5 = true
}
switch l := e.X.(type) {
case *ast.BinaryExpr:
if l.Op.Precedence() < e.Op.Precedence() {
// parens will be inserted.
// pretend this is an *ast.ParenExpr and do nothing.
break
}
h4, h5, mp := walkBinary(l)
has4 = has4 || h4
has5 = has5 || h5
if maxProblem < mp {
maxProblem = mp
}
}
switch r := e.Y.(type) {
case *ast.BinaryExpr:
if r.Op.Precedence() <= e.Op.Precedence() {
// parens will be inserted.
// pretend this is an *ast.ParenExpr and do nothing.
break
}
h4, h5, mp := walkBinary(r)
has4 = has4 || h4
has5 = has5 || h5
if maxProblem < mp {
maxProblem = mp
}
case *ast.StarExpr:
if e.Op == token.QUO { // `*/`
maxProblem = 5
}
case *ast.UnaryExpr:
switch e.Op.String() + r.Op.String() {
case "/*", "&&", "&^":
maxProblem = 5
case "++", "--":
if maxProblem < 4 {
maxProblem = 4
}
}
}
return
}
func cutoff(e *ast.BinaryExpr, depth int) int {
has4, has5, maxProblem := walkBinary(e)
if maxProblem > 0 {
return maxProblem + 1
}
if has4 && has5 {
if depth == 1 {
return 5
}
return 4
}
if depth == 1 {
return 6
}
return 4
}
func diffPrec(expr ast.Expr, prec int) int {
x, ok := expr.(*ast.BinaryExpr)
if !ok || prec != x.Op.Precedence() {
return 1
}
return 0
}
func reduceDepth(depth int) int {
depth--
if depth < 1 {
depth = 1
}
return depth
}
// Format the binary expression: decide the cutoff and then format.
// Let's call depth == 1 Normal mode, and depth > 1 Compact mode.
// (Algorithm suggestion by Russ Cox.)
//
// The precedences are:
//
// 5 * / % << >> & &^
// 4 + - | ^
// 3 == != < <= > >=
// 2 &&
// 1 ||
//
// The only decision is whether there will be spaces around levels 4 and 5.
// There are never spaces at level 6 (unary), and always spaces at levels 3 and below.
//
// To choose the cutoff, look at the whole expression but excluding primary
// expressions (function calls, parenthesized exprs), and apply these rules:
//
// 1. If there is a binary operator with a right side unary operand
// that would clash without a space, the cutoff must be (in order):
//
// /* 6
// && 6
// &^ 6
// ++ 5
// -- 5
//
// (Comparison operators always have spaces around them.)
//
// 2. If there is a mix of level 5 and level 4 operators, then the cutoff
// is 5 (use spaces to distinguish precedence) in Normal mode
// and 4 (never use spaces) in Compact mode.
//
// 3. If there are no level 4 operators or no level 5 operators, then the
// cutoff is 6 (always use spaces) in Normal mode
// and 4 (never use spaces) in Compact mode.
func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1, cutoff, depth int) {
prec := x.Op.Precedence()
if prec < prec1 {
// parenthesis needed
// Note: The parser inserts an ast.ParenExpr node; thus this case
// can only occur if the AST is created in a different way.
p.print(token.LPAREN)
p.expr0(x, reduceDepth(depth)) // parentheses undo one level of depth
p.print(token.RPAREN)
return
}
printBlank := prec < cutoff
ws := indent
p.expr1(x.X, prec, depth+diffPrec(x.X, prec))
if printBlank {
p.print(blank)
}
xline := p.pos.Line // before the operator (it may be on the next line!)
yline := p.lineFor(x.Y.Pos())
p.print(x.OpPos, x.Op)
if xline != yline && xline > 0 && yline > 0 {
// at least one line break, but respect an extra empty line
// in the source
if p.linebreak(yline, 1, ws, true) > 0 {
ws = ignore
printBlank = false // no blank after line break
}
}
if printBlank {
p.print(blank)
}
p.expr1(x.Y, prec+1, depth+1)
if ws == ignore {
p.print(unindent)
}
}
func isBinary(expr ast.Expr) bool {
_, ok := expr.(*ast.BinaryExpr)
return ok
}
func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
p.print(expr.Pos())
switch x := expr.(type) {
case *ast.BadExpr:
p.print("BadExpr")
case *ast.Ident:
p.print(x)
case *ast.BinaryExpr:
if depth < 1 {
p.internalError("depth < 1:", depth)
depth = 1
}
p.binaryExpr(x, prec1, cutoff(x, depth), depth)
case *ast.KeyValueExpr:
p.expr(x.Key)
p.print(x.Colon, token.COLON, blank)
p.expr(x.Value)
case *ast.StarExpr:
const prec = token.UnaryPrec
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN)
p.print(token.MUL)
p.expr(x.X)
p.print(token.RPAREN)
} else {
// no parenthesis needed
p.print(token.MUL)
p.expr(x.X)
}
case *ast.UnaryExpr:
const prec = token.UnaryPrec
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN)
p.expr(x)
p.print(token.RPAREN)
} else {
// no parenthesis needed
p.print(x.Op)
if x.Op == token.RANGE {
// TODO(gri) Remove this code if it cannot be reached.
p.print(blank)
}
p.expr1(x.X, prec, depth)
}
case *ast.BasicLit:
if p.Config.Mode&normalizeNumbers != 0 {
x = normalizedNumber(x)
}
p.print(x)
case *ast.FuncLit:
p.print(x.Type.Pos(), token.FUNC)
// See the comment in funcDecl about how the header size is computed.
startCol := p.out.Column - len("func")
p.signature(x.Type)
p.funcBody(p.distanceFrom(x.Type.Pos(), startCol), blank, x.Body)
case *ast.ParenExpr:
if _, hasParens := x.X.(*ast.ParenExpr); hasParens {
// don't print parentheses around an already parenthesized expression
// TODO(gri) consider making this more general and incorporate precedence levels
p.expr0(x.X, depth)
} else {
p.print(token.LPAREN)
p.expr0(x.X, reduceDepth(depth)) // parentheses undo one level of depth
p.print(x.Rparen, token.RPAREN)
}
case *ast.SelectorExpr:
p.selectorExpr(x, depth, false)
case *ast.TypeAssertExpr:
p.expr1(x.X, token.HighestPrec, depth)
p.print(token.PERIOD, x.Lparen, token.LPAREN)
if x.Type != nil {
p.expr(x.Type)
} else {
p.print(token.TYPE)
}
p.print(x.Rparen, token.RPAREN)
case *ast.IndexExpr:
// TODO(gri): should treat[] like parentheses and undo one level of depth
p.expr1(x.X, token.HighestPrec, 1)
p.print(x.Lbrack, token.LBRACK)
p.expr0(x.Index, depth+1)
p.print(x.Rbrack, token.RBRACK)
case *ast.IndexListExpr:
// TODO(gri): as for IndexExpr, should treat [] like parentheses and undo
// one level of depth
p.expr1(x.X, token.HighestPrec, 1)
p.print(x.Lbrack, token.LBRACK)
p.exprList(x.Lbrack, x.Indices, depth+1, commaTerm, x.Rbrack, false)
p.print(x.Rbrack, token.RBRACK)
case *ast.SliceExpr:
// TODO(gri): should treat[] like parentheses and undo one level of depth
p.expr1(x.X, token.HighestPrec, 1)
p.print(x.Lbrack, token.LBRACK)
indices := []ast.Expr{x.Low, x.High}
if x.Max != nil {
indices = append(indices, x.Max)
}
// determine if we need extra blanks around ':'
var needsBlanks bool
if depth <= 1 {
var indexCount int
var hasBinaries bool
for _, x := range indices {
if x != nil {
indexCount++
if isBinary(x) {
hasBinaries = true
}
}
}
if indexCount > 1 && hasBinaries {
needsBlanks = true
}
}
for i, x := range indices {
if i > 0 {
if indices[i-1] != nil && needsBlanks {
p.print(blank)
}
p.print(token.COLON)
if x != nil && needsBlanks {
p.print(blank)
}
}
if x != nil {
p.expr0(x, depth+1)
}
}
p.print(x.Rbrack, token.RBRACK)
case *ast.CallExpr:
if len(x.Args) > 1 {
depth++
}
var wasIndented bool
if _, ok := x.Fun.(*ast.FuncType); ok {
// conversions to literal function types require parentheses around the type
p.print(token.LPAREN)
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
p.print(token.RPAREN)
} else {
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
}
p.print(x.Lparen, token.LPAREN)
if x.Ellipsis.IsValid() {
p.exprList(x.Lparen, x.Args, depth, 0, x.Ellipsis, false)
p.print(x.Ellipsis, token.ELLIPSIS)
if x.Rparen.IsValid() && p.lineFor(x.Ellipsis) < p.lineFor(x.Rparen) {
p.print(token.COMMA, formfeed)
}
} else {
p.exprList(x.Lparen, x.Args, depth, commaTerm, x.Rparen, false)
}
p.print(x.Rparen, token.RPAREN)
if wasIndented {
p.print(unindent)
}
case *ast.CompositeLit:
// composite literal elements that are composite literals themselves may have the type omitted
if x.Type != nil {
p.expr1(x.Type, token.HighestPrec, depth)
}
p.level++
p.print(x.Lbrace, token.LBRACE)
p.exprList(x.Lbrace, x.Elts, 1, commaTerm, x.Rbrace, x.Incomplete)
// do not insert extra line break following a /*-style comment
// before the closing '}' as it might break the code if there
// is no trailing ','
mode := noExtraLinebreak
// do not insert extra blank following a /*-style comment
// before the closing '}' unless the literal is empty
if len(x.Elts) > 0 {
mode |= noExtraBlank
}
// need the initial indent to print lone comments with
// the proper level of indentation
p.print(indent, unindent, mode, x.Rbrace, token.RBRACE, mode)
p.level--
case *ast.Ellipsis:
p.print(token.ELLIPSIS)
if x.Elt != nil {
p.expr(x.Elt)
}
case *ast.ArrayType:
p.print(token.LBRACK)
if x.Len != nil {
p.expr(x.Len)
}
p.print(token.RBRACK)