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Commit 6e98b7f0 authored by Robert Griesemer's avatar Robert Griesemer
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split printer.go into two files; it has become too large: 

- nodes.go implements ast node formatting
- printer.go implements the core printing functionality
  and public interface

No code changes except for updating the import clauses
and adding a top-level comment to nodes.go.

R=rsc
http://go/go-review/1016026
parent 120d0b50
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Inline Side-by-side
Showing with 1085 additions and 1070 deletions
src/pkg/go/printer/Makefile
View file @ 6e98b7f0
......@@ -7,5 +7,6 @@ include $(GOROOT)/src/Make.$(GOARCH)
TARG=go/printer
GOFILES=\
printer.go\
nodes.go\
include $(GOROOT)/src/Make.pkg
src/pkg/go/printer/nodes.go 0 → 100644
View file @ 6e98b7f0
// 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";
"container/vector";
"go/ast";
"go/token";
)
// ----------------------------------------------------------------------------
// Common AST nodes.
// Print as many newlines as necessary (but at least min and and at most
// max 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 true if any line break was printed; returns false otherwise.
//
// TODO(gri): Reconsider signature (provide position instead of line)
//
func (p *printer) linebreak(line, min, max int, ws whiteSpace, newSection bool) (printedBreak bool) {
n := line - p.pos.Line;
switch {
case n < min: n = min;
case n > max: n = max;
}
if n > 0 {
p.print(ws);
if newSection {
p.print(formfeed);
n--;
printedBreak = true;
}
}
for ; n > 0; n-- {
p.print(newline);
printedBreak = true;
}
return;
}
// TODO(gri): The code for printing lead and line comments
// should be eliminated in favor of reusing the
// comment intersperse mechanism above somehow.
// Print a list of individual comments.
func (p *printer) commentList(list []*ast.Comment) {
for i, c := range list {
t := c.Text;
// TODO(gri): this needs to be styled like normal comments
p.print(c.Pos(), t);
if t[1] == '/' && i+1 < len(list) {
//-style comment which is not at the end; print a newline
p.print(newline);
}
}
}
// Print a lead comment followed by a newline.
func (p *printer) leadComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.commentList(d.List);
p.print(newline);
}
}
// Print a tab followed by a line comment.
// A newline must be printed afterwards since
// the comment may be a //-style comment.
func (p *printer) lineComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.print(vtab);
p.commentList(d.List);
}
}
// Sets multiLine to true if the identifier list spans multiple lines.
func (p *printer) identList(list []*ast.Ident, multiLine *bool) {
// convert into an expression list
xlist := make([]ast.Expr, len(list));
for i, x := range list {
xlist[i] = x;
}
p.exprList(noPos, xlist, commaSep, multiLine);
}
// Sets multiLine to true if the string list spans multiple lines.
func (p *printer) stringList(list []*ast.BasicLit, multiLine *bool) {
// convert into an expression list
xlist := make([]ast.Expr, len(list));
for i, x := range list {
xlist[i] = x;
}
p.exprList(noPos, xlist, noIndent, multiLine);
}
type exprListMode uint;
const (
blankStart exprListMode = 1 << iota; // print a blank before the list
commaSep; // elements are separated by commas
commaTerm; // elements are terminated by comma
noIndent; // no extra indentation in multi-line lists
)
// Print a list of expressions. If the list spans multiple
// source lines, the original line breaks are respected between
// expressions. Sets multiLine to true if the list spans multiple
// lines.
func (p *printer) exprList(prev token.Position, list []ast.Expr, mode exprListMode, multiLine *bool) {
if len(list) == 0 {
return;
}
if mode & blankStart != 0 {
p.print(blank);
}
// TODO(gri): endLine may be incorrect as it is really the beginning
// of the last list entry. There may be only one, very long
// entry in which case line == endLine.
line := list[0].Pos().Line;
endLine := list[len(list)-1].Pos().Line;
if prev.IsValid() && prev.Line == line && line == endLine {
// all list entries on a single line
for i, x := range list {
if i > 0 {
if mode & commaSep != 0 {
p.print(token.COMMA);
}
p.print(blank);
}
p.expr(x, multiLine);
}
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;
}
if prev.IsValid() && prev.Line < line && p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
for i, x := range list {
prev := line;
line = x.Pos().Line;
if i > 0 {
if mode & commaSep != 0 {
p.print(token.COMMA);
}
if prev < line {
if p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
} else {
p.print(blank);
}
}
p.expr(x, multiLine);
}
if mode & commaTerm != 0 {
p.print(token.COMMA);
if ws == ignore && mode&noIndent == 0 {
// should always be indented here since we have a multi-line
// expression list - be conservative and check anyway
p.print(unindent);
}
p.print(formfeed); // terminating comma needs a line break to look good
} else if ws == ignore && mode&noIndent == 0 {
p.print(unindent);
}
}
// Sets multiLine to true if the the parameter list spans multiple lines.
func (p *printer) parameters(list []*ast.Field, multiLine *bool) {
p.print(token.LPAREN);
if len(list) > 0 {
for i, par := range list {
if i > 0 {
p.print(token.COMMA, blank);
}
if len(par.Names) > 0 {
p.identList(par.Names, multiLine);
p.print(blank);
}
p.expr(par.Type, multiLine);
}
}
p.print(token.RPAREN);
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the signature spans multiple lines.
func (p *printer) signature(params, result []*ast.Field, multiLine *bool) (optSemi bool) {
p.parameters(params, multiLine);
if result != nil {
p.print(blank);
if len(result) == 1 && result[0].Names == nil {
// single anonymous result; no ()'s unless it's a function type
f := result[0];
if _, isFtyp := f.Type.(*ast.FuncType); !isFtyp {
optSemi = p.expr(f.Type, multiLine);
return;
}
}
p.parameters(result, multiLine);
}
return;
}
func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace token.Position, isIncomplete, isStruct bool) {
if len(list) == 0 && !isIncomplete && !p.commentBefore(rbrace) {
// no blank between keyword and {} in this case
p.print(lbrace, token.LBRACE, rbrace, token.RBRACE);
return;
}
// at least one entry or incomplete
p.print(blank, lbrace, token.LBRACE, indent, formfeed);
if isStruct {
sep := vtab;
if len(list) == 1 {
sep = blank;
}
for i, f := range list {
extraTabs := 0;
p.leadComment(f.Doc);
if len(f.Names) > 0 {
p.identList(f.Names, ignoreMultiLine);
p.print(sep);
p.expr(f.Type, ignoreMultiLine);
extraTabs = 1;
} else {
p.expr(f.Type, ignoreMultiLine);
extraTabs = 2;
}
if f.Tag != nil {
if len(f.Names) > 0 && sep == vtab {
p.print(sep);
}
p.print(sep);
p.expr(&ast.StringList{f.Tag}, ignoreMultiLine);
extraTabs = 0;
}
p.print(token.SEMICOLON);
if f.Comment != nil {
for ; extraTabs > 0; extraTabs-- {
p.print(vtab);
}
p.lineComment(f.Comment);
}
if i+1 < len(list) || isIncomplete {
p.print(newline);
}
}
if isIncomplete {
// TODO(gri): this needs to be styled like normal comments
p.print("// contains unexported fields");
}
} else { // interface
for i, f := range list {
p.leadComment(f.Doc);
if ftyp, isFtyp := f.Type.(*ast.FuncType); isFtyp {
// method
p.expr(f.Names[0], ignoreMultiLine); // exactly one name
p.signature(ftyp.Params, ftyp.Results, ignoreMultiLine);
} else {
// embedded interface
p.expr(f.Type, ignoreMultiLine);
}
p.print(token.SEMICOLON);
p.lineComment(f.Comment);
if i+1 < len(list) || isIncomplete {
p.print(newline);
}
}
if isIncomplete {
// TODO(gri): this needs to be styled like normal comments
p.print("// contains unexported methods");
}
}
p.print(unindent, formfeed, rbrace, token.RBRACE);
}
// ----------------------------------------------------------------------------
// Expressions
func needsBlanks(expr ast.Expr) bool {
switch x := expr.(type) {
case *ast.Ident:
// "long" identifiers look better with blanks around them
return len(x.Value) > 8;
case *ast.BasicLit:
// "long" literals look better with blanks around them
return len(x.Value) > 8;
case *ast.ParenExpr:
// parenthesized expressions don't need blanks around them
return false;
case *ast.IndexExpr:
// index expressions don't need blanks if the indexed expressions are simple
return needsBlanks(x.X)
case *ast.CallExpr:
// call expressions need blanks if they have more than one
// argument or if the function expression needs blanks
return len(x.Args) > 1 || needsBlanks(x.Fun);
}
return true;
}
// Sets multiLine to true if the binary expression spans multiple lines.
func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1 int, multiLine *bool) {
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.expr(x, multiLine);
p.print(token.RPAREN);
return;
}
// Traverse left, collect all operations at same precedence
// and determine if blanks should be printed around operators.
//
// This algorithm assumes that the right-hand side of a binary
// operation has a different (higher) precedence then the current
// node, which is how the parser creates the AST.
var list vector.Vector;
line := x.Y.Pos().Line;
printBlanks := prec <= token.EQL.Precedence() || needsBlanks(x.Y);
for {
list.Push(x);
if t, ok := x.X.(*ast.BinaryExpr); ok && t.Op.Precedence() == prec {
x = t;
prev := line;
line = x.Y.Pos().Line;
if needsBlanks(x.Y) || prev != line {
printBlanks = true;
}
} else {
break;
}
}
prev := line;
line = x.X.Pos().Line;
if needsBlanks(x.X) || prev != line {
printBlanks = true;
}
// Print collected operations left-to-right, with blanks if necessary.
ws := indent;
p.expr1(x.X, prec, multiLine);
for list.Len() > 0 {
x = list.Pop().(*ast.BinaryExpr);
prev := line;
line = x.Y.Pos().Line;
if printBlanks {
if prev != line {
p.print(blank, x.OpPos, x.Op);
// at least one line break, but respect an extra empty line
// in the source
if p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
} else {
p.print(blank, x.OpPos, x.Op, blank);
}
} else {
if prev != line {
panic("internal error");
}
p.print(x.OpPos, x.Op);
}
p.expr1(x.Y, prec, multiLine);
}
if ws == ignore {
p.print(unindent);
}
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool) {
p.print(expr.Pos());
switch x := expr.(type) {
case *ast.BadExpr:
p.print("BadExpr");
case *ast.Ident:
p.print(x);
case *ast.BinaryExpr:
p.binaryExpr(x, prec1, multiLine);
case *ast.KeyValueExpr:
p.expr(x.Key, multiLine);
p.print(x.Colon, token.COLON, blank);
p.expr(x.Value, multiLine);
case *ast.StarExpr:
p.print(token.MUL);
optSemi = p.expr(x.X, multiLine);
case *ast.UnaryExpr:
const prec = token.UnaryPrec;
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN);
p.expr(x, multiLine);
p.print(token.RPAREN);
} else {
// no parenthesis needed
p.print(x.Op);
if x.Op == token.RANGE {
p.print(blank);
}
p.expr1(x.X, prec, multiLine);
}
case *ast.BasicLit:
p.print(x);
case *ast.StringList:
p.stringList(x.Strings, multiLine);
case *ast.FuncLit:
p.expr(x.Type, multiLine);
p.funcBody(x.Body, true, multiLine);
case *ast.ParenExpr:
p.print(token.LPAREN);
p.expr(x.X, multiLine);
p.print(x.Rparen, token.RPAREN);
case *ast.SelectorExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.PERIOD);
p.expr1(x.Sel, token.HighestPrec, multiLine);
case *ast.TypeAssertExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.PERIOD, token.LPAREN);
if x.Type != nil {
p.expr(x.Type, multiLine);
} else {
p.print(token.TYPE);
}
p.print(token.RPAREN);
case *ast.IndexExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.LBRACK);
p.expr1(x.Index, token.LowestPrec, multiLine);
if x.End != nil {
if needsBlanks(x.Index) || needsBlanks(x.End) {
// blanks around ":"
p.print(blank, token.COLON, blank);
} else {
// no blanks around ":"
p.print(token.COLON);
}
p.expr(x.End, multiLine);
}
p.print(token.RBRACK);
case *ast.CallExpr:
p.expr1(x.Fun, token.HighestPrec, multiLine);
p.print(x.Lparen, token.LPAREN);
p.exprList(x.Lparen, x.Args, commaSep, multiLine);
p.print(x.Rparen, token.RPAREN);
case *ast.CompositeLit:
p.expr1(x.Type, token.HighestPrec, multiLine);
p.print(x.Lbrace, token.LBRACE);
p.exprList(x.Lbrace, x.Elts, commaSep|commaTerm, multiLine);
p.print(x.Rbrace, token.RBRACE);
case *ast.Ellipsis:
p.print(token.ELLIPSIS);
case *ast.ArrayType:
p.print(token.LBRACK);
if x.Len != nil {
p.expr(x.Len, multiLine);
}
p.print(token.RBRACK);
optSemi = p.expr(x.Elt, multiLine);
case *ast.StructType:
p.print(token.STRUCT);
p.fieldList(x.Lbrace, x.Fields, x.Rbrace, x.Incomplete, true);
optSemi = true;
case *ast.FuncType:
p.print(token.FUNC);
optSemi = p.signature(x.Params, x.Results, multiLine);
case *ast.InterfaceType:
p.print(token.INTERFACE);
p.fieldList(x.Lbrace, x.Methods, x.Rbrace, x.Incomplete, false);
optSemi = true;
case *ast.MapType:
p.print(token.MAP, token.LBRACK);
p.expr(x.Key, multiLine);
p.print(token.RBRACK);
optSemi = p.expr(x.Value, multiLine);
case *ast.ChanType:
switch x.Dir {
case ast.SEND | ast.RECV:
p.print(token.CHAN);
case ast.RECV:
p.print(token.ARROW, token.CHAN);
case ast.SEND:
p.print(token.CHAN, token.ARROW);
}
p.print(blank);
optSemi = p.expr(x.Value, multiLine);
default:
panic("unreachable");
}
return;
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr(x ast.Expr, multiLine *bool) (optSemi bool) {
return p.expr1(x, token.LowestPrec, multiLine);
}
// ----------------------------------------------------------------------------
// Statements
const maxStmtNewlines = 2 // maximum number of newlines between statements
// Print the statement list indented, but without a newline after the last statement.
// Extra line breaks between statements in the source are respected but at most one
// empty line is printed between statements.
func (p *printer) stmtList(list []ast.Stmt, _indent int) {
// TODO(gri): fix _indent code
if _indent > 0 {
p.print(indent);
}
var multiLine bool;
for i, s := range list {
// _indent == 0 only for lists of switch/select case clauses;
// in those cases each clause is a new section
p.linebreak(s.Pos().Line, 1, maxStmtNewlines, ignore, i == 0 || _indent == 0 || multiLine);
multiLine = false;
if !p.stmt(s, &multiLine) {
p.print(token.SEMICOLON);
}
}
if _indent > 0 {
p.print(unindent);
}
}
// Sets multiLine to true if the block spans multiple lines.
func (p *printer) block(s *ast.BlockStmt, indent int, multiLine *bool) {
p.print(s.Pos(), token.LBRACE);
if len(s.List) > 0 || p.commentBefore(s.Rbrace) {
p.stmtList(s.List, indent);
p.linebreak(s.Rbrace.Line, 1, maxStmtNewlines, ignore, true);
}
p.print(s.Rbrace, token.RBRACE);
}
// TODO(gri): Decide if this should be used more broadly. The printing code
// knows when to insert parentheses for precedence reasons, but
// need to be careful to keep them around type expressions.
func stripParens(x ast.Expr) ast.Expr {
if px, hasParens := x.(*ast.ParenExpr); hasParens {
return stripParens(px.X);
}
return x;
}
func (p *printer) controlClause(isForStmt bool, init ast.Stmt, expr ast.Expr, post ast.Stmt) {
p.print(blank);
needsBlank := false;
if init == nil && post == nil {
// no semicolons required
if expr != nil {
p.expr(stripParens(expr), ignoreMultiLine);
needsBlank = true;
}
} else {
// all semicolons required
// (they are not separators, print them explicitly)
if init != nil {
p.stmt(init, ignoreMultiLine);
}
p.print(token.SEMICOLON, blank);
if expr != nil {
p.expr(stripParens(expr), ignoreMultiLine);
needsBlank = true;
}
if isForStmt {
p.print(token.SEMICOLON, blank);
needsBlank = false;
if post != nil {
p.stmt(post, ignoreMultiLine);
needsBlank = true;
}
}
}
if needsBlank {
p.print(blank);
}
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the statements spans multiple lines.
func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
p.print(stmt.Pos());
switch s := stmt.(type) {
case *ast.BadStmt:
p.print("BadStmt");
case *ast.DeclStmt:
p.decl(s.Decl, inStmtList, multiLine);
optSemi = true; // decl prints terminating semicolon if necessary
case *ast.EmptyStmt:
// nothing to do
case *ast.LabeledStmt:
// a "correcting" unindent immediately following a line break
// is applied before the line break if there is no comment
// between (see writeWhitespace)
p.print(unindent);
p.expr(s.Label, multiLine);
p.print(token.COLON, vtab, indent);
p.linebreak(s.Stmt.Pos().Line, 0, 1, ignore, true);
optSemi = p.stmt(s.Stmt, multiLine);
case *ast.ExprStmt:
p.expr(s.X, multiLine);
case *ast.IncDecStmt:
p.expr(s.X, multiLine);
p.print(s.Tok);
case *ast.AssignStmt:
p.exprList(s.Pos(), s.Lhs, commaSep, multiLine);
p.print(blank, s.TokPos, s.Tok);
p.exprList(s.TokPos, s.Rhs, blankStart | commaSep, multiLine);
case *ast.GoStmt:
p.print(token.GO, blank);
p.expr(s.Call, multiLine);
case *ast.DeferStmt:
p.print(token.DEFER, blank);
p.expr(s.Call, multiLine);
case *ast.ReturnStmt:
p.print(token.RETURN);
if s.Results != nil {
p.exprList(s.Pos(), s.Results, blankStart | commaSep, multiLine);
}
case *ast.BranchStmt:
p.print(s.Tok);
if s.Label != nil {
p.print(blank);
p.expr(s.Label, multiLine);
}
case *ast.BlockStmt:
p.block(s, 1, multiLine);
optSemi = true;
case *ast.IfStmt:
p.print(token.IF);
p.controlClause(false, s.Init, s.Cond, nil);
p.block(s.Body, 1, multiLine);
optSemi = true;
if s.Else != nil {
p.print(blank, token.ELSE, blank);
switch s.Else.(type) {
case *ast.BlockStmt, *ast.IfStmt:
optSemi = p.stmt(s.Else, multiLine);
default:
p.print(token.LBRACE, indent, formfeed);
p.stmt(s.Else, ignoreMultiLine);
p.print(unindent, formfeed, token.RBRACE);
*multiLine = true;
}
}
case *ast.CaseClause:
if s.Values != nil {
p.print(token.CASE);
p.exprList(s.Pos(), s.Values, blankStart | commaSep, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.SwitchStmt:
p.print(token.SWITCH);
p.controlClause(false, s.Init, s.Tag, nil);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.TypeCaseClause:
if s.Types != nil {
p.print(token.CASE);
p.exprList(s.Pos(), s.Types, blankStart | commaSep, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.TypeSwitchStmt:
p.print(token.SWITCH);
if s.Init != nil {
p.print(blank);
p.stmt(s.Init, multiLine);
p.print(token.SEMICOLON);
}
p.print(blank);
p.stmt(s.Assign, multiLine);
p.print(blank);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.CommClause:
if s.Rhs != nil {
p.print(token.CASE, blank);
if s.Lhs != nil {
p.expr(s.Lhs, multiLine);
p.print(blank, s.Tok, blank);
}
p.expr(s.Rhs, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.SelectStmt:
p.print(token.SELECT, blank);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.ForStmt:
p.print(token.FOR);
p.controlClause(true, s.Init, s.Cond, s.Post);
p.block(s.Body, 1, multiLine);
optSemi = true;
case *ast.RangeStmt:
p.print(token.FOR, blank);
p.expr(s.Key, multiLine);
if s.Value != nil {
p.print(token.COMMA, blank);
p.expr(s.Value, multiLine);
}
p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank);
p.expr(s.X, multiLine);
p.print(blank);
p.block(s.Body, 1, multiLine);
optSemi = true;
default:
panic("unreachable");
}
return;
}
// ----------------------------------------------------------------------------
// Declarations
type declContext uint;
const (
atTop declContext = iota;
inGroup;
inStmtList;
)
// The parameter n is the number of specs in the group; context specifies
// the surroundings of the declaration. Separating semicolons are printed
// depending on the context. Sets multiLine to true if the spec spans
// multiple lines.
//
func (p *printer) spec(spec ast.Spec, n int, context declContext, multiLine *bool) {
var (
optSemi bool; // true if a semicolon is optional
comment *ast.CommentGroup; // a line comment, if any
extraTabs int; // number of extra tabs before comment, if any
)
switch s := spec.(type) {
case *ast.ImportSpec:
p.leadComment(s.Doc);
if s.Name != nil {
p.expr(s.Name, multiLine);
p.print(blank);
}
p.expr(&ast.StringList{s.Path}, multiLine);
comment = s.Comment;
case *ast.ValueSpec:
p.leadComment(s.Doc);
p.identList(s.Names, multiLine); // always present
if n == 1 {
if s.Type != nil {
p.print(blank);
optSemi = p.expr(s.Type, multiLine);
}
if s.Values != nil {
p.print(blank, token.ASSIGN);
p.exprList(noPos, s.Values, blankStart | commaSep, multiLine);
optSemi = false;
}
} else {
extraTabs = 2;
if s.Type != nil || s.Values != nil {
p.print(vtab);
}
if s.Type != nil {
optSemi = p.expr(s.Type, multiLine);
extraTabs = 1;
}
if s.Values != nil {
p.print(vtab);
p.print(token.ASSIGN);
p.exprList(noPos, s.Values, blankStart | commaSep, multiLine);
optSemi = false;
extraTabs = 0;
}
}
comment = s.Comment;
case *ast.TypeSpec:
p.leadComment(s.Doc);
p.expr(s.Name, multiLine);
if n == 1 {
p.print(blank);
} else {
p.print(vtab);
}
optSemi = p.expr(s.Type, multiLine);
comment = s.Comment;
default:
panic("unreachable");
}
if context == inGroup || context == inStmtList && !optSemi {
p.print(token.SEMICOLON);
}
if comment != nil {
for ; extraTabs > 0; extraTabs-- {
p.print(vtab);
}
p.lineComment(comment);
}
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) genDecl(d *ast.GenDecl, context declContext, multiLine *bool) {
p.leadComment(d.Doc);
p.print(d.Pos(), d.Tok, blank);
if d.Lparen.IsValid() {
// group of parenthesized declarations
p.print(d.Lparen, token.LPAREN);
if len(d.Specs) > 0 {
p.print(indent, formfeed);
var ml bool;
for i, s := range d.Specs {
if i > 0 {
if ml {
p.print(formfeed);
} else {
p.print(newline);
}
}
ml = false;
p.spec(s, len(d.Specs), inGroup, &ml);
}
p.print(unindent, formfeed);
*multiLine = true;
}
p.print(d.Rparen, token.RPAREN);
} else {
// single declaration
p.spec(d.Specs[0], 1, context, multiLine);
}
}
func (p *printer) isOneLiner(b *ast.BlockStmt) bool {
if len(b.List) != 1 || p.commentBefore(b.Rbrace) {
// too many statements or there is a comment - all bets are off
return false;
}
// test-print the statement and see if it would fit
var buf bytes.Buffer;
_, err := p.Config.Fprint(&buf, b.List[0]);
if err != nil {
return false; // don't try
}
if buf.Len() > 40 {
return false; // too long
}
for _, ch := range buf.Bytes() {
if ch < ' ' {
return false; // contains control chars (tabs, newlines)
}
}
return true;
}
// Sets multiLine to true if the function body spans multiple lines.
func (p *printer) funcBody(b *ast.BlockStmt, isLit bool, multiLine *bool) {
if b == nil {
return;
}
// TODO(gri): enable for function declarations, eventually.
if isLit && p.isOneLiner(b) {
sep := vtab;
if isLit {
sep = blank;
}
p.print(sep, b.Pos(), token.LBRACE, blank);
p.stmt(b.List[0], ignoreMultiLine);
p.print(blank, b.Rbrace, token.RBRACE);
return;
}
p.print(blank);
p.block(b, 1, multiLine);
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) funcDecl(d *ast.FuncDecl, multiLine *bool) {
p.leadComment(d.Doc);
p.print(d.Pos(), token.FUNC, blank);
if recv := d.Recv; recv != nil {
// method: print receiver
p.print(token.LPAREN);
if len(recv.Names) > 0 {
p.expr(recv.Names[0], multiLine);
p.print(blank);
}
p.expr(recv.Type, multiLine);
p.print(token.RPAREN, blank);
}
p.expr(d.Name, multiLine);
p.signature(d.Type.Params, d.Type.Results, multiLine);
p.funcBody(d.Body, false, multiLine);
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) decl(decl ast.Decl, context declContext, multiLine *bool) {
switch d := decl.(type) {
case *ast.BadDecl:
p.print(d.Pos(), "BadDecl");
case *ast.GenDecl:
p.genDecl(d, context, multiLine);
case *ast.FuncDecl:
p.funcDecl(d, multiLine);
default:
panic("unreachable");
}
}
// ----------------------------------------------------------------------------
// Files
const maxDeclNewlines = 3 // maximum number of newlines between declarations
func declToken(decl ast.Decl) (tok token.Token) {
tok = token.ILLEGAL;
switch d := decl.(type) {
case *ast.GenDecl:
tok = d.Tok;
case *ast.FuncDecl:
tok = token.FUNC;
}
return;
}
func (p *printer) file(src *ast.File) {
p.leadComment(src.Doc);
p.print(src.Pos(), token.PACKAGE, blank);
p.expr(src.Name, ignoreMultiLine);
if len(src.Decls) > 0 {
tok := token.ILLEGAL;
for _, d := range src.Decls {
prev := tok;
tok = declToken(d);
// if the declaration token changed (e.g., from CONST to TYPE)
// print an empty line between top-level declarations
min := 1;
if prev != tok {
min = 2;
}
p.linebreak(d.Pos().Line, min, maxDeclNewlines, ignore, false);
p.decl(d, atTop, ignoreMultiLine);
}
}
p.print(newline);
}
src/pkg/go/printer/printer.go
View file @ 6e98b7f0
......@@ -7,7 +7,6 @@ package printer
import (
"bytes";
"container/vector";
"fmt";
"go/ast";
"go/token";
......@@ -627,7 +626,7 @@ func (p *printer) writeWhitespace(n int) {
// print prints a list of "items" (roughly corresponding to syntactic
// tokens, but also including whitespace and formatting information).
// It is the only print function that should be called directly from
// any of the AST printing functions below.
// any of the AST printing functions in nodes.go.
//
// Whitespace is accumulated until a non-whitespace token appears. Any
// comments that need to appear before that token are printed first,
......@@ -738,1074 +737,6 @@ func (p *printer) flush(next token.Position, isKeyword bool) {
}
// ----------------------------------------------------------------------------
// Printing of common AST nodes.
// Print as many newlines as necessary (but at least min and and at most
// max 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 true if any line break was printed; returns false otherwise.
//
// TODO(gri): Reconsider signature (provide position instead of line)
//
func (p *printer) linebreak(line, min, max int, ws whiteSpace, newSection bool) (printedBreak bool) {
n := line - p.pos.Line;
switch {
case n < min: n = min;
case n > max: n = max;
}
if n > 0 {
p.print(ws);
if newSection {
p.print(formfeed);
n--;
printedBreak = true;
}
}
for ; n > 0; n-- {
p.print(newline);
printedBreak = true;
}
return;
}
// TODO(gri): The code for printing lead and line comments
// should be eliminated in favor of reusing the
// comment intersperse mechanism above somehow.
// Print a list of individual comments.
func (p *printer) commentList(list []*ast.Comment) {
for i, c := range list {
t := c.Text;
// TODO(gri): this needs to be styled like normal comments
p.print(c.Pos(), t);
if t[1] == '/' && i+1 < len(list) {
//-style comment which is not at the end; print a newline
p.print(newline);
}
}
}
// Print a lead comment followed by a newline.
func (p *printer) leadComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.commentList(d.List);
p.print(newline);
}
}
// Print a tab followed by a line comment.
// A newline must be printed afterwards since
// the comment may be a //-style comment.
func (p *printer) lineComment(d *ast.CommentGroup) {
// Ignore the comment if we have comments interspersed (p.comment != nil).
if p.comment == nil && d != nil {
p.print(vtab);
p.commentList(d.List);
}
}
// Sets multiLine to true if the identifier list spans multiple lines.
func (p *printer) identList(list []*ast.Ident, multiLine *bool) {
// convert into an expression list
xlist := make([]ast.Expr, len(list));
for i, x := range list {
xlist[i] = x;
}
p.exprList(noPos, xlist, commaSep, multiLine);
}
// Sets multiLine to true if the string list spans multiple lines.
func (p *printer) stringList(list []*ast.BasicLit, multiLine *bool) {
// convert into an expression list
xlist := make([]ast.Expr, len(list));
for i, x := range list {
xlist[i] = x;
}
p.exprList(noPos, xlist, noIndent, multiLine);
}
type exprListMode uint;
const (
blankStart exprListMode = 1 << iota; // print a blank before the list
commaSep; // elements are separated by commas
commaTerm; // elements are terminated by comma
noIndent; // no extra indentation in multi-line lists
)
// Print a list of expressions. If the list spans multiple
// source lines, the original line breaks are respected between
// expressions. Sets multiLine to true if the list spans multiple
// lines.
func (p *printer) exprList(prev token.Position, list []ast.Expr, mode exprListMode, multiLine *bool) {
if len(list) == 0 {
return;
}
if mode & blankStart != 0 {
p.print(blank);
}
// TODO(gri): endLine may be incorrect as it is really the beginning
// of the last list entry. There may be only one, very long
// entry in which case line == endLine.
line := list[0].Pos().Line;
endLine := list[len(list)-1].Pos().Line;
if prev.IsValid() && prev.Line == line && line == endLine {
// all list entries on a single line
for i, x := range list {
if i > 0 {
if mode & commaSep != 0 {
p.print(token.COMMA);
}
p.print(blank);
}
p.expr(x, multiLine);
}
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;
}
if prev.IsValid() && prev.Line < line && p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
for i, x := range list {
prev := line;
line = x.Pos().Line;
if i > 0 {
if mode & commaSep != 0 {
p.print(token.COMMA);
}
if prev < line {
if p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
} else {
p.print(blank);
}
}
p.expr(x, multiLine);
}
if mode & commaTerm != 0 {
p.print(token.COMMA);
if ws == ignore && mode&noIndent == 0 {
// should always be indented here since we have a multi-line
// expression list - be conservative and check anyway
p.print(unindent);
}
p.print(formfeed); // terminating comma needs a line break to look good
} else if ws == ignore && mode&noIndent == 0 {
p.print(unindent);
}
}
// Sets multiLine to true if the the parameter list spans multiple lines.
func (p *printer) parameters(list []*ast.Field, multiLine *bool) {
p.print(token.LPAREN);
if len(list) > 0 {
for i, par := range list {
if i > 0 {
p.print(token.COMMA, blank);
}
if len(par.Names) > 0 {
p.identList(par.Names, multiLine);
p.print(blank);
}
p.expr(par.Type, multiLine);
}
}
p.print(token.RPAREN);
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the signature spans multiple lines.
func (p *printer) signature(params, result []*ast.Field, multiLine *bool) (optSemi bool) {
p.parameters(params, multiLine);
if result != nil {
p.print(blank);
if len(result) == 1 && result[0].Names == nil {
// single anonymous result; no ()'s unless it's a function type
f := result[0];
if _, isFtyp := f.Type.(*ast.FuncType); !isFtyp {
optSemi = p.expr(f.Type, multiLine);
return;
}
}
p.parameters(result, multiLine);
}
return;
}
func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace token.Position, isIncomplete, isStruct bool) {
if len(list) == 0 && !isIncomplete && !p.commentBefore(rbrace) {
// no blank between keyword and {} in this case
p.print(lbrace, token.LBRACE, rbrace, token.RBRACE);
return;
}
// at least one entry or incomplete
p.print(blank, lbrace, token.LBRACE, indent, formfeed);
if isStruct {
sep := vtab;
if len(list) == 1 {
sep = blank;
}
for i, f := range list {
extraTabs := 0;
p.leadComment(f.Doc);
if len(f.Names) > 0 {
p.identList(f.Names, ignoreMultiLine);
p.print(sep);
p.expr(f.Type, ignoreMultiLine);
extraTabs = 1;
} else {
p.expr(f.Type, ignoreMultiLine);
extraTabs = 2;
}
if f.Tag != nil {
if len(f.Names) > 0 && sep == vtab {
p.print(sep);
}
p.print(sep);
p.expr(&ast.StringList{f.Tag}, ignoreMultiLine);
extraTabs = 0;
}
p.print(token.SEMICOLON);
if f.Comment != nil {
for ; extraTabs > 0; extraTabs-- {
p.print(vtab);
}
p.lineComment(f.Comment);
}
if i+1 < len(list) || isIncomplete {
p.print(newline);
}
}
if isIncomplete {
// TODO(gri): this needs to be styled like normal comments
p.print("// contains unexported fields");
}
} else { // interface
for i, f := range list {
p.leadComment(f.Doc);
if ftyp, isFtyp := f.Type.(*ast.FuncType); isFtyp {
// method
p.expr(f.Names[0], ignoreMultiLine); // exactly one name
p.signature(ftyp.Params, ftyp.Results, ignoreMultiLine);
} else {
// embedded interface
p.expr(f.Type, ignoreMultiLine);
}
p.print(token.SEMICOLON);
p.lineComment(f.Comment);
if i+1 < len(list) || isIncomplete {
p.print(newline);
}
}
if isIncomplete {
// TODO(gri): this needs to be styled like normal comments
p.print("// contains unexported methods");
}
}
p.print(unindent, formfeed, rbrace, token.RBRACE);
}
// ----------------------------------------------------------------------------
// Expressions
func needsBlanks(expr ast.Expr) bool {
switch x := expr.(type) {
case *ast.Ident:
// "long" identifiers look better with blanks around them
return len(x.Value) > 8;
case *ast.BasicLit:
// "long" literals look better with blanks around them
return len(x.Value) > 8;
case *ast.ParenExpr:
// parenthesized expressions don't need blanks around them
return false;
case *ast.IndexExpr:
// index expressions don't need blanks if the indexed expressions are simple
return needsBlanks(x.X)
case *ast.CallExpr:
// call expressions need blanks if they have more than one
// argument or if the function expression needs blanks
return len(x.Args) > 1 || needsBlanks(x.Fun);
}
return true;
}
// Sets multiLine to true if the binary expression spans multiple lines.
func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1 int, multiLine *bool) {
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.expr(x, multiLine);
p.print(token.RPAREN);
return;
}
// Traverse left, collect all operations at same precedence
// and determine if blanks should be printed around operators.
//
// This algorithm assumes that the right-hand side of a binary
// operation has a different (higher) precedence then the current
// node, which is how the parser creates the AST.
var list vector.Vector;
line := x.Y.Pos().Line;
printBlanks := prec <= token.EQL.Precedence() || needsBlanks(x.Y);
for {
list.Push(x);
if t, ok := x.X.(*ast.BinaryExpr); ok && t.Op.Precedence() == prec {
x = t;
prev := line;
line = x.Y.Pos().Line;
if needsBlanks(x.Y) || prev != line {
printBlanks = true;
}
} else {
break;
}
}
prev := line;
line = x.X.Pos().Line;
if needsBlanks(x.X) || prev != line {
printBlanks = true;
}
// Print collected operations left-to-right, with blanks if necessary.
ws := indent;
p.expr1(x.X, prec, multiLine);
for list.Len() > 0 {
x = list.Pop().(*ast.BinaryExpr);
prev := line;
line = x.Y.Pos().Line;
if printBlanks {
if prev != line {
p.print(blank, x.OpPos, x.Op);
// at least one line break, but respect an extra empty line
// in the source
if p.linebreak(line, 1, 2, ws, true) {
ws = ignore;
*multiLine = true;
}
} else {
p.print(blank, x.OpPos, x.Op, blank);
}
} else {
if prev != line {
panic("internal error");
}
p.print(x.OpPos, x.Op);
}
p.expr1(x.Y, prec, multiLine);
}
if ws == ignore {
p.print(unindent);
}
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool) {
p.print(expr.Pos());
switch x := expr.(type) {
case *ast.BadExpr:
p.print("BadExpr");
case *ast.Ident:
p.print(x);
case *ast.BinaryExpr:
p.binaryExpr(x, prec1, multiLine);
case *ast.KeyValueExpr:
p.expr(x.Key, multiLine);
p.print(x.Colon, token.COLON, blank);
p.expr(x.Value, multiLine);
case *ast.StarExpr:
p.print(token.MUL);
optSemi = p.expr(x.X, multiLine);
case *ast.UnaryExpr:
const prec = token.UnaryPrec;
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN);
p.expr(x, multiLine);
p.print(token.RPAREN);
} else {
// no parenthesis needed
p.print(x.Op);
if x.Op == token.RANGE {
p.print(blank);
}
p.expr1(x.X, prec, multiLine);
}
case *ast.BasicLit:
p.print(x);
case *ast.StringList:
p.stringList(x.Strings, multiLine);
case *ast.FuncLit:
p.expr(x.Type, multiLine);
p.funcBody(x.Body, true, multiLine);
case *ast.ParenExpr:
p.print(token.LPAREN);
p.expr(x.X, multiLine);
p.print(x.Rparen, token.RPAREN);
case *ast.SelectorExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.PERIOD);
p.expr1(x.Sel, token.HighestPrec, multiLine);
case *ast.TypeAssertExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.PERIOD, token.LPAREN);
if x.Type != nil {
p.expr(x.Type, multiLine);
} else {
p.print(token.TYPE);
}
p.print(token.RPAREN);
case *ast.IndexExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.print(token.LBRACK);
p.expr1(x.Index, token.LowestPrec, multiLine);
if x.End != nil {
if needsBlanks(x.Index) || needsBlanks(x.End) {
// blanks around ":"
p.print(blank, token.COLON, blank);
} else {
// no blanks around ":"
p.print(token.COLON);
}
p.expr(x.End, multiLine);
}
p.print(token.RBRACK);
case *ast.CallExpr:
p.expr1(x.Fun, token.HighestPrec, multiLine);
p.print(x.Lparen, token.LPAREN);
p.exprList(x.Lparen, x.Args, commaSep, multiLine);
p.print(x.Rparen, token.RPAREN);
case *ast.CompositeLit:
p.expr1(x.Type, token.HighestPrec, multiLine);
p.print(x.Lbrace, token.LBRACE);
p.exprList(x.Lbrace, x.Elts, commaSep|commaTerm, multiLine);
p.print(x.Rbrace, token.RBRACE);
case *ast.Ellipsis:
p.print(token.ELLIPSIS);
case *ast.ArrayType:
p.print(token.LBRACK);
if x.Len != nil {
p.expr(x.Len, multiLine);
}
p.print(token.RBRACK);
optSemi = p.expr(x.Elt, multiLine);
case *ast.StructType:
p.print(token.STRUCT);
p.fieldList(x.Lbrace, x.Fields, x.Rbrace, x.Incomplete, true);
optSemi = true;
case *ast.FuncType:
p.print(token.FUNC);
optSemi = p.signature(x.Params, x.Results, multiLine);
case *ast.InterfaceType:
p.print(token.INTERFACE);
p.fieldList(x.Lbrace, x.Methods, x.Rbrace, x.Incomplete, false);
optSemi = true;
case *ast.MapType:
p.print(token.MAP, token.LBRACK);
p.expr(x.Key, multiLine);
p.print(token.RBRACK);
optSemi = p.expr(x.Value, multiLine);
case *ast.ChanType:
switch x.Dir {
case ast.SEND | ast.RECV:
p.print(token.CHAN);
case ast.RECV:
p.print(token.ARROW, token.CHAN);
case ast.SEND:
p.print(token.CHAN, token.ARROW);
}
p.print(blank);
optSemi = p.expr(x.Value, multiLine);
default:
panic("unreachable");
}
return;
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr(x ast.Expr, multiLine *bool) (optSemi bool) {
return p.expr1(x, token.LowestPrec, multiLine);
}
// ----------------------------------------------------------------------------
// Statements
const maxStmtNewlines = 2 // maximum number of newlines between statements
// Print the statement list indented, but without a newline after the last statement.
// Extra line breaks between statements in the source are respected but at most one
// empty line is printed between statements.
func (p *printer) stmtList(list []ast.Stmt, _indent int) {
// TODO(gri): fix _indent code
if _indent > 0 {
p.print(indent);
}
var multiLine bool;
for i, s := range list {
// _indent == 0 only for lists of switch/select case clauses;
// in those cases each clause is a new section
p.linebreak(s.Pos().Line, 1, maxStmtNewlines, ignore, i == 0 || _indent == 0 || multiLine);
multiLine = false;
if !p.stmt(s, &multiLine) {
p.print(token.SEMICOLON);
}
}
if _indent > 0 {
p.print(unindent);
}
}
// Sets multiLine to true if the block spans multiple lines.
func (p *printer) block(s *ast.BlockStmt, indent int, multiLine *bool) {
p.print(s.Pos(), token.LBRACE);
if len(s.List) > 0 || p.commentBefore(s.Rbrace) {
p.stmtList(s.List, indent);
p.linebreak(s.Rbrace.Line, 1, maxStmtNewlines, ignore, true);
}
p.print(s.Rbrace, token.RBRACE);
}
// TODO(gri): Decide if this should be used more broadly. The printing code
// knows when to insert parentheses for precedence reasons, but
// need to be careful to keep them around type expressions.
func stripParens(x ast.Expr) ast.Expr {
if px, hasParens := x.(*ast.ParenExpr); hasParens {
return stripParens(px.X);
}
return x;
}
func (p *printer) controlClause(isForStmt bool, init ast.Stmt, expr ast.Expr, post ast.Stmt) {
p.print(blank);
needsBlank := false;
if init == nil && post == nil {
// no semicolons required
if expr != nil {
p.expr(stripParens(expr), ignoreMultiLine);
needsBlank = true;
}
} else {
// all semicolons required
// (they are not separators, print them explicitly)
if init != nil {
p.stmt(init, ignoreMultiLine);
}
p.print(token.SEMICOLON, blank);
if expr != nil {
p.expr(stripParens(expr), ignoreMultiLine);
needsBlank = true;
}
if isForStmt {
p.print(token.SEMICOLON, blank);
needsBlank = false;
if post != nil {
p.stmt(post, ignoreMultiLine);
needsBlank = true;
}
}
}
if needsBlank {
p.print(blank);
}
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the statements spans multiple lines.
func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
p.print(stmt.Pos());
switch s := stmt.(type) {
case *ast.BadStmt:
p.print("BadStmt");
case *ast.DeclStmt:
p.decl(s.Decl, inStmtList, multiLine);
optSemi = true; // decl prints terminating semicolon if necessary
case *ast.EmptyStmt:
// nothing to do
case *ast.LabeledStmt:
// a "correcting" unindent immediately following a line break
// is applied before the line break if there is no comment
// between (see writeWhitespace)
p.print(unindent);
p.expr(s.Label, multiLine);
p.print(token.COLON, vtab, indent);
p.linebreak(s.Stmt.Pos().Line, 0, 1, ignore, true);
optSemi = p.stmt(s.Stmt, multiLine);
case *ast.ExprStmt:
p.expr(s.X, multiLine);
case *ast.IncDecStmt:
p.expr(s.X, multiLine);
p.print(s.Tok);
case *ast.AssignStmt:
p.exprList(s.Pos(), s.Lhs, commaSep, multiLine);
p.print(blank, s.TokPos, s.Tok);
p.exprList(s.TokPos, s.Rhs, blankStart | commaSep, multiLine);
case *ast.GoStmt:
p.print(token.GO, blank);
p.expr(s.Call, multiLine);
case *ast.DeferStmt:
p.print(token.DEFER, blank);
p.expr(s.Call, multiLine);
case *ast.ReturnStmt:
p.print(token.RETURN);
if s.Results != nil {
p.exprList(s.Pos(), s.Results, blankStart | commaSep, multiLine);
}
case *ast.BranchStmt:
p.print(s.Tok);
if s.Label != nil {
p.print(blank);
p.expr(s.Label, multiLine);
}
case *ast.BlockStmt:
p.block(s, 1, multiLine);
optSemi = true;
case *ast.IfStmt:
p.print(token.IF);
p.controlClause(false, s.Init, s.Cond, nil);
p.block(s.Body, 1, multiLine);
optSemi = true;
if s.Else != nil {
p.print(blank, token.ELSE, blank);
switch s.Else.(type) {
case *ast.BlockStmt, *ast.IfStmt:
optSemi = p.stmt(s.Else, multiLine);
default:
p.print(token.LBRACE, indent, formfeed);
p.stmt(s.Else, ignoreMultiLine);
p.print(unindent, formfeed, token.RBRACE);
*multiLine = true;
}
}
case *ast.CaseClause:
if s.Values != nil {
p.print(token.CASE);
p.exprList(s.Pos(), s.Values, blankStart | commaSep, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.SwitchStmt:
p.print(token.SWITCH);
p.controlClause(false, s.Init, s.Tag, nil);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.TypeCaseClause:
if s.Types != nil {
p.print(token.CASE);
p.exprList(s.Pos(), s.Types, blankStart | commaSep, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.TypeSwitchStmt:
p.print(token.SWITCH);
if s.Init != nil {
p.print(blank);
p.stmt(s.Init, multiLine);
p.print(token.SEMICOLON);
}
p.print(blank);
p.stmt(s.Assign, multiLine);
p.print(blank);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.CommClause:
if s.Rhs != nil {
p.print(token.CASE, blank);
if s.Lhs != nil {
p.expr(s.Lhs, multiLine);
p.print(blank, s.Tok, blank);
}
p.expr(s.Rhs, multiLine);
} else {
p.print(token.DEFAULT);
}
p.print(s.Colon, token.COLON);
p.stmtList(s.Body, 1);
optSemi = true; // "block" without {}'s
case *ast.SelectStmt:
p.print(token.SELECT, blank);
p.block(s.Body, 0, multiLine);
optSemi = true;
case *ast.ForStmt:
p.print(token.FOR);
p.controlClause(true, s.Init, s.Cond, s.Post);
p.block(s.Body, 1, multiLine);
optSemi = true;
case *ast.RangeStmt:
p.print(token.FOR, blank);
p.expr(s.Key, multiLine);
if s.Value != nil {
p.print(token.COMMA, blank);
p.expr(s.Value, multiLine);
}
p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank);
p.expr(s.X, multiLine);
p.print(blank);
p.block(s.Body, 1, multiLine);
optSemi = true;
default:
panic("unreachable");
}
return;
}
// ----------------------------------------------------------------------------
// Declarations
type declContext uint;
const (
atTop declContext = iota;
inGroup;
inStmtList;
)
// The parameter n is the number of specs in the group; context specifies
// the surroundings of the declaration. Separating semicolons are printed
// depending on the context. Sets multiLine to true if the spec spans
// multiple lines.
//
func (p *printer) spec(spec ast.Spec, n int, context declContext, multiLine *bool) {
var (
optSemi bool; // true if a semicolon is optional
comment *ast.CommentGroup; // a line comment, if any
extraTabs int; // number of extra tabs before comment, if any
)
switch s := spec.(type) {
case *ast.ImportSpec:
p.leadComment(s.Doc);
if s.Name != nil {
p.expr(s.Name, multiLine);
p.print(blank);
}
p.expr(&ast.StringList{s.Path}, multiLine);
comment = s.Comment;
case *ast.ValueSpec:
p.leadComment(s.Doc);
p.identList(s.Names, multiLine); // always present
if n == 1 {
if s.Type != nil {
p.print(blank);
optSemi = p.expr(s.Type, multiLine);
}
if s.Values != nil {
p.print(blank, token.ASSIGN);
p.exprList(noPos, s.Values, blankStart | commaSep, multiLine);
optSemi = false;
}
} else {
extraTabs = 2;
if s.Type != nil || s.Values != nil {
p.print(vtab);
}
if s.Type != nil {
optSemi = p.expr(s.Type, multiLine);
extraTabs = 1;
}
if s.Values != nil {
p.print(vtab);
p.print(token.ASSIGN);
p.exprList(noPos, s.Values, blankStart | commaSep, multiLine);
optSemi = false;
extraTabs = 0;
}
}
comment = s.Comment;
case *ast.TypeSpec:
p.leadComment(s.Doc);
p.expr(s.Name, multiLine);
if n == 1 {
p.print(blank);
} else {
p.print(vtab);
}
optSemi = p.expr(s.Type, multiLine);
comment = s.Comment;
default:
panic("unreachable");
}
if context == inGroup || context == inStmtList && !optSemi {
p.print(token.SEMICOLON);
}
if comment != nil {
for ; extraTabs > 0; extraTabs-- {
p.print(vtab);
}
p.lineComment(comment);
}
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) genDecl(d *ast.GenDecl, context declContext, multiLine *bool) {
p.leadComment(d.Doc);
p.print(d.Pos(), d.Tok, blank);
if d.Lparen.IsValid() {
// group of parenthesized declarations
p.print(d.Lparen, token.LPAREN);
if len(d.Specs) > 0 {
p.print(indent, formfeed);
var ml bool;
for i, s := range d.Specs {
if i > 0 {
if ml {
p.print(formfeed);
} else {
p.print(newline);
}
}
ml = false;
p.spec(s, len(d.Specs), inGroup, &ml);
}
p.print(unindent, formfeed);
*multiLine = true;
}
p.print(d.Rparen, token.RPAREN);
} else {
// single declaration
p.spec(d.Specs[0], 1, context, multiLine);
}
}
func (p *printer) isOneLiner(b *ast.BlockStmt) bool {
if len(b.List) != 1 || p.commentBefore(b.Rbrace) {
// too many statements or there is a comment - all bets are off
return false;
}
// test-print the statement and see if it would fit
var buf bytes.Buffer;
_, err := p.Config.Fprint(&buf, b.List[0]);
if err != nil {
return false; // don't try
}
if buf.Len() > 40 {
return false; // too long
}
for _, ch := range buf.Bytes() {
if ch < ' ' {
return false; // contains control chars (tabs, newlines)
}
}
return true;
}
// Sets multiLine to true if the function body spans multiple lines.
func (p *printer) funcBody(b *ast.BlockStmt, isLit bool, multiLine *bool) {
if b == nil {
return;
}
// TODO(gri): enable for function declarations, eventually.
if isLit && p.isOneLiner(b) {
sep := vtab;
if isLit {
sep = blank;
}
p.print(sep, b.Pos(), token.LBRACE, blank);
p.stmt(b.List[0], ignoreMultiLine);
p.print(blank, b.Rbrace, token.RBRACE);
return;
}
p.print(blank);
p.block(b, 1, multiLine);
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) funcDecl(d *ast.FuncDecl, multiLine *bool) {
p.leadComment(d.Doc);
p.print(d.Pos(), token.FUNC, blank);
if recv := d.Recv; recv != nil {
// method: print receiver
p.print(token.LPAREN);
if len(recv.Names) > 0 {
p.expr(recv.Names[0], multiLine);
p.print(blank);
}
p.expr(recv.Type, multiLine);
p.print(token.RPAREN, blank);
}
p.expr(d.Name, multiLine);
p.signature(d.Type.Params, d.Type.Results, multiLine);
p.funcBody(d.Body, false, multiLine);
}
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) decl(decl ast.Decl, context declContext, multiLine *bool) {
switch d := decl.(type) {
case *ast.BadDecl:
p.print(d.Pos(), "BadDecl");
case *ast.GenDecl:
p.genDecl(d, context, multiLine);
case *ast.FuncDecl:
p.funcDecl(d, multiLine);
default:
panic("unreachable");
}
}
// ----------------------------------------------------------------------------
// Files
const maxDeclNewlines = 3 // maximum number of newlines between declarations
func declToken(decl ast.Decl) (tok token.Token) {
tok = token.ILLEGAL;
switch d := decl.(type) {
case *ast.GenDecl:
tok = d.Tok;
case *ast.FuncDecl:
tok = token.FUNC;
}
return;
}
func (p *printer) file(src *ast.File) {
p.leadComment(src.Doc);
p.print(src.Pos(), token.PACKAGE, blank);
p.expr(src.Name, ignoreMultiLine);
if len(src.Decls) > 0 {
tok := token.ILLEGAL;
for _, d := range src.Decls {
prev := tok;
tok = declToken(d);
// if the declaration token changed (e.g., from CONST to TYPE)
// print an empty line between top-level declarations
min := 1;
if prev != tok {
min = 2;
}
p.linebreak(d.Pos().Line, min, maxDeclNewlines, ignore, false);
p.decl(d, atTop, ignoreMultiLine);
}
}
p.print(newline);
}
// ----------------------------------------------------------------------------
// Trimmer
......
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