// fprint implements Fprint and takes a nodesSizes map for setting up the printer state.
func (cfg *Config) fprint(output io.Writer, fset *token.FileSet, node interface{}, nodeSizes map[ast.Node]int) (written int, err error) {
// redirect output through a trimmer to eliminate trailing whitespace
// (Input to a tabwriter must be untrimmed since trailing tabs provide
// formatting information. The tabwriter could provide trimming
// functionality but no tabwriter is used when RawFormat is set.)
output = &trimmer{output: output}
// setup tabwriter if needed and redirect output
var tw *tabwriter.Writer
if cfg.Mode&RawFormat == 0 {
minwidth := cfg.Tabwidth
padchar := byte('\t')
if cfg.Mode&UseSpaces != 0 {
padchar = ' '
}
twmode := tabwriter.DiscardEmptyColumns
if cfg.Mode&TabIndent != 0 {
minwidth = 0
twmode |= tabwriter.TabIndent
}
tw = tabwriter.NewWriter(output, minwidth, cfg.Tabwidth, 1, padchar, twmode)
output = tw
}
// setup printer
var p printer
p.init(output, cfg, fset, nodeSizes)
defer func() {
written = p.written
if e := recover(); e != nil {
err = e.(osError).err // re-panics if it's not a local osError
}
}()
// print node
switch n := node.(type) {
case ast.Expr:
p.useNodeComments = true
p.expr(n, ignoreMultiLine)
case ast.Stmt:
p.useNodeComments = true
// A labeled statement will un-indent to position the
// label. Set indent to 1 so we don't get indent "underflow".
if _, labeledStmt := n.(*ast.LabeledStmt); labeledStmt {
p.indent = 1
}
p.stmt(n, false, ignoreMultiLine)
case ast.Decl:
p.useNodeComments = true
p.decl(n, ignoreMultiLine)
case ast.Spec:
p.useNodeComments = true
p.spec(n, 1, false, ignoreMultiLine)
case *ast.File:
p.comments = n.Comments
p.useNodeComments = n.Comments == nil
p.file(n)
default:
panic(osError{fmt.Errorf("printer.Fprint: unsupported node type %T", n)})
}
p.flush(token.Position{Offset: infinity, Line: infinity}, token.EOF)
// flush tabwriter, if any
if tw != nil {
tw.Flush() // ignore errors
}
return
}
// Fprint "pretty-prints" an AST node to output and returns the number
// of bytes written and an error (if any) for a given configuration cfg.
// Position information is interpreted relative to the file set fset.
// The node type must be *ast.File, or assignment-compatible to ast.Expr,
// ast.Decl, ast.Spec, or ast.Stmt.
//
func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node interface{}) (int, os.Error) {
// redirect output through a trimmer to eliminate trailing whitespace
// (Input to a tabwriter must be untrimmed since trailing tabs provide
// formatting information. The tabwriter could provide trimming
// functionality but no tabwriter is used when RawFormat is set.)
output = &trimmer{output: output}
// setup tabwriter if needed and redirect output
var tw *tabwriter.Writer
if cfg.Mode&RawFormat == 0 {
minwidth := cfg.Tabwidth
padchar := byte('\t')
if cfg.Mode&UseSpaces != 0 {
padchar = ' '
}
twmode := tabwriter.DiscardEmptyColumns
if cfg.Mode&TabIndent != 0 {
minwidth = 0
twmode |= tabwriter.TabIndent
}
tw = tabwriter.NewWriter(output, minwidth, cfg.Tabwidth, 1, padchar, twmode)
output = tw
}
// setup printer and print node
var p printer
p.init(output, cfg, fset)
go func() {
switch n := node.(type) {
case ast.Expr:
p.nesting = 1
p.useNodeComments = true
p.expr(n, ignoreMultiLine)
case ast.Stmt:
p.nesting = 1
p.useNodeComments = true
// A labeled statement will un-indent to position the
// label. Set indent to 1 so we don't get indent "underflow".
if _, labeledStmt := n.(*ast.LabeledStmt); labeledStmt {
p.indent = 1
}
p.stmt(n, false, ignoreMultiLine)
case ast.Decl:
p.nesting = 1
p.useNodeComments = true
p.decl(n, ignoreMultiLine)
case ast.Spec:
p.nesting = 1
p.useNodeComments = true
p.spec(n, 1, false, ignoreMultiLine)
case *ast.File:
p.nesting = 0
p.comments = n.Comments
p.useNodeComments = n.Comments == nil
p.file(n)
default:
p.errors <- fmt.Errorf("printer.Fprint: unsupported node type %T", n)
runtime.Goexit()
}
p.flush(token.Position{Offset: infinity, Line: infinity}, token.EOF)
p.errors <- nil // no errors
}()
err := <-p.errors // wait for completion of goroutine
// flush tabwriter, if any
if tw != nil {
tw.Flush() // ignore errors
}
return p.written, err
}