mirror of
https://github.com/golang/go
synced 2024-11-23 04:20:03 -07:00
539 lines
9.6 KiB
Go
539 lines
9.6 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package Printer
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import Strings "strings"
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import Scanner "scanner"
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import AST "ast"
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export type Printer struct {
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pos int; // actual output position
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// formatting control
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level int; // true scope level
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indent int; // indentation level
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semi bool; // pending ";"
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newl int; // pending "\n"'s
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// comments
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clist *AST.List;
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cindex int;
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cpos int;
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}
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// Bottleneck interface - all output goes through here.
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func (P *Printer) print(s string) {
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print(s);
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// TODO do we need the code below?
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// P.pos += Strings.utflen(s);
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}
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func (P *Printer) String(pos int, s string) {
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if P.semi && P.level > 0 { // no semicolons at level 0
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print(";");
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}
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/*
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for pos > P.cpos {
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// we have a comment
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c := P.clist.at(P.cindex).(*AST.Comment);
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if c.text[1] == '/' {
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print(" " + c.text);
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if P.newl <= 0 {
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P.newl = 1; // line comments must have a newline
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}
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} else {
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print(c.text);
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}
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P.cindex++;
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if P.cindex < P.clist.len() {
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P.cpos = P.clist.at(P.cindex).(*AST.Comment).pos;
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} else {
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P.cpos = 1000000000; // infinite
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}
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}
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*/
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if P.newl > 0 {
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for i := P.newl; i > 0; i-- {
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print("\n");
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}
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for i := P.indent; i > 0; i-- {
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print("\t");
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}
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}
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print(s);
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P.semi, P.newl = false, 0;
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}
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func (P *Printer) Blank() {
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P.String(0, " ");
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}
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func (P *Printer) Token(pos int, tok int) {
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P.String(pos, Scanner.TokenString(tok));
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}
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func (P *Printer) OpenScope(paren string) {
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//P.semi, P.newl = false, 0;
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P.String(0, paren);
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P.level++;
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P.indent++;
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P.newl = 1;
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}
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func (P *Printer) CloseScope(paren string) {
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P.indent--;
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P.semi = false;
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P.String(0, paren);
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P.level--;
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P.semi, P.newl = false, 1;
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}
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func (P *Printer) Error(pos int, tok int, msg string) {
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P.String(0, "<");
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P.Token(pos, tok);
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P.String(0, " " + msg + ">");
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}
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// ----------------------------------------------------------------------------
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// Types
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func (P *Printer) Type(t *AST.Type)
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func (P *Printer) Expr(x *AST.Expr)
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func (P *Printer) Parameters(pos int, list *AST.List) {
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P.String(pos, "(");
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var prev int;
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for i, n := 0, list.len(); i < n; i++ {
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x := list.at(i).(*AST.Expr);
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if i > 0 {
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if prev == x.tok || prev == Scanner.TYPE {
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P.String(0, ", ");
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} else {
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P.Blank();
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}
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}
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P.Expr(x);
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prev = x.tok;
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}
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P.String(0, ")");
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}
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func (P *Printer) Fields(list *AST.List) {
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P.OpenScope("{");
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var prev int;
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for i, n := 0, list.len(); i < n; i++ {
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x := list.at(i).(*AST.Expr);
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if i > 0 {
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if prev == Scanner.TYPE && x.tok != Scanner.STRING || prev == Scanner.STRING {
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P.semi, P.newl = true, 1;
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} else if prev == x.tok {
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P.String(0, ", ");
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} else {
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P.Blank();
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}
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}
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P.Expr(x);
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prev = x.tok;
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}
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P.newl = 1;
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P.CloseScope("}");
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}
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func (P *Printer) Type(t *AST.Type) {
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switch t.tok {
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case Scanner.IDENT:
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P.Expr(t.expr);
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case Scanner.LBRACK:
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P.String(t.pos, "[");
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if t.expr != nil {
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P.Expr(t.expr);
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}
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P.String(0, "]");
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P.Type(t.elt);
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case Scanner.STRUCT, Scanner.INTERFACE:
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P.Token(t.pos, t.tok);
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if t.list != nil {
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P.Blank();
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P.Fields(t.list);
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}
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case Scanner.MAP:
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P.String(t.pos, "map [");
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P.Type(t.key);
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P.String(0, "]");
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P.Type(t.elt);
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case Scanner.CHAN:
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var m string;
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switch t.mode {
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case AST.FULL: m = "chan ";
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case AST.RECV: m = "<-chan ";
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case AST.SEND: m = "chan <- ";
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}
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P.String(t.pos, m);
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P.Type(t.elt);
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case Scanner.MUL:
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P.String(t.pos, "*");
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P.Type(t.elt);
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case Scanner.LPAREN:
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P.Parameters(t.pos, t.list);
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if t.elt != nil {
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P.Blank();
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P.Parameters(0, t.elt.list);
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}
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case Scanner.ELLIPSIS:
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P.String(t.pos, "...");
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default:
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P.Error(t.pos, t.tok, "type");
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}
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}
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// ----------------------------------------------------------------------------
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// Expressions
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func (P *Printer) Block(list *AST.List, indent bool);
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func (P *Printer) Expr1(x *AST.Expr, prec1 int) {
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if x == nil {
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return; // empty expression list
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}
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switch x.tok {
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case Scanner.TYPE:
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// type expr
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P.Type(x.t);
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case Scanner.IDENT, Scanner.INT, Scanner.STRING, Scanner.FLOAT:
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// literal
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P.String(x.pos, x.s);
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case Scanner.FUNC:
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// function literal
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P.String(x.pos, "func");
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P.Type(x.t);
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P.Block(x.block, true);
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P.newl = 0;
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case Scanner.COMMA:
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// list
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// (don't use binary expression printing because of different spacing)
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P.Expr(x.x);
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P.String(x.pos, ", ");
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P.Expr(x.y);
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case Scanner.PERIOD:
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// selector or type guard
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P.Expr1(x.x, Scanner.HighestPrec);
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P.String(x.pos, ".");
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if x.y != nil {
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P.Expr1(x.y, Scanner.HighestPrec);
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} else {
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P.String(0, "(");
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P.Type(x.t);
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P.String(0, ")");
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}
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case Scanner.LBRACK:
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// index
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P.Expr1(x.x, Scanner.HighestPrec);
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P.String(x.pos, "[");
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P.Expr1(x.y, 0);
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P.String(0, "]");
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case Scanner.LPAREN:
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// call
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P.Expr1(x.x, Scanner.HighestPrec);
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P.String(x.pos, "(");
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P.Expr(x.y);
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P.String(0, ")");
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case Scanner.LBRACE:
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// composite
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P.Type(x.t);
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P.String(x.pos, "{");
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P.Expr(x.y);
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P.String(0, "}");
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default:
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// unary and binary expressions including ":" for pairs
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prec := Scanner.UnaryPrec;
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if x.x != nil {
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prec = Scanner.Precedence(x.tok);
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}
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if prec < prec1 {
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P.String(0, "(");
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}
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if x.x == nil {
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// unary expression
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P.Token(x.pos, x.tok);
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} else {
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// binary expression
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P.Expr1(x.x, prec);
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P.Blank();
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P.Token(x.pos, x.tok);
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P.Blank();
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}
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P.Expr1(x.y, prec);
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if prec < prec1 {
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P.String(0, ")");
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}
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}
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}
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func (P *Printer) Expr(x *AST.Expr) {
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P.Expr1(x, Scanner.LowestPrec);
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}
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// ----------------------------------------------------------------------------
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// Statements
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func (P *Printer) Stat(s *AST.Stat)
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func (P *Printer) StatementList(list *AST.List) {
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for i, n := 0, list.len(); i < n; i++ {
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P.Stat(list.at(i).(*AST.Stat));
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P.newl = 1;
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}
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}
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func (P *Printer) Block(list *AST.List, indent bool) {
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P.OpenScope("{");
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if !indent {
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P.indent--;
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}
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P.StatementList(list);
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if !indent {
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P.indent++;
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}
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P.CloseScope("}");
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}
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func (P *Printer) ControlClause(s *AST.Stat) {
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has_post := s.tok == Scanner.FOR && s.post != nil; // post also used by "if"
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if s.init == nil && !has_post {
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// no semicolons required
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if s.expr != nil {
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P.Blank();
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P.Expr(s.expr);
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}
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} else {
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// all semicolons required
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P.Blank();
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if s.init != nil {
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P.Stat(s.init);
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}
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P.semi = true;
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P.Blank();
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if s.expr != nil {
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P.Expr(s.expr);
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}
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if s.tok == Scanner.FOR {
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P.semi = true;
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if has_post {
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P.Blank();
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P.Stat(s.post);
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P.semi = false
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}
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}
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}
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P.Blank();
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}
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func (P *Printer) Declaration(d *AST.Decl, parenthesized bool);
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func (P *Printer) Stat(s *AST.Stat) {
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switch s.tok {
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case Scanner.EXPRSTAT:
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// expression statement
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P.Expr(s.expr);
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P.semi = true;
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case Scanner.COLON:
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// label declaration
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P.indent--;
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P.Expr(s.expr);
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P.Token(s.pos, s.tok);
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P.indent++;
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P.semi = false;
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case Scanner.CONST, Scanner.TYPE, Scanner.VAR:
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// declaration
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P.Declaration(s.decl, false);
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case Scanner.INC, Scanner.DEC:
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P.Expr(s.expr);
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P.Token(s.pos, s.tok);
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P.semi = true;
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case Scanner.LBRACE:
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// block
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P.Block(s.block, true);
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case Scanner.IF:
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P.String(s.pos, "if");
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P.ControlClause(s);
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P.Block(s.block, true);
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if s.post != nil {
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P.newl = 0;
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P.String(0, " else ");
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P.Stat(s.post);
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}
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case Scanner.FOR:
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P.String(s.pos, "for");
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P.ControlClause(s);
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P.Block(s.block, true);
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case Scanner.SWITCH, Scanner.SELECT:
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P.Token(s.pos, s.tok);
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P.ControlClause(s);
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P.Block(s.block, false);
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case Scanner.CASE, Scanner.DEFAULT:
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P.Token(s.pos, s.tok);
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if s.expr != nil {
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P.Blank();
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P.Expr(s.expr);
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}
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P.String(0, ":");
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P.indent++;
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P.newl = 1;
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P.StatementList(s.block);
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P.indent--;
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P.newl = 1;
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case Scanner.GO, Scanner.RETURN, Scanner.FALLTHROUGH, Scanner.BREAK, Scanner.CONTINUE, Scanner.GOTO:
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P.Token(s.pos, s.tok);
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if s.expr != nil {
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P.Blank();
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P.Expr(s.expr);
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}
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P.semi = true;
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default:
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P.Error(s.pos, s.tok, "stat");
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}
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}
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// ----------------------------------------------------------------------------
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// Declarations
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func (P *Printer) Declaration(d *AST.Decl, parenthesized bool) {
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if !parenthesized {
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if d.exported {
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P.String(0, "export ");
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}
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P.Token(d.pos, d.tok);
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P.Blank();
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}
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if d.tok != Scanner.FUNC && d.list != nil {
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P.OpenScope("(");
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for i := 0; i < d.list.len(); i++ {
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P.Declaration(d.list.at(i).(*AST.Decl), true);
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P.semi, P.newl = true, 1;
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}
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P.CloseScope(")");
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} else {
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if d.tok == Scanner.FUNC && d.typ.key != nil {
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P.Parameters(0, d.typ.key.list);
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P.Blank();
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}
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P.Expr(d.ident);
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if d.typ != nil {
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P.Blank();
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P.Type(d.typ);
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}
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if d.val != nil {
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if d.tok == Scanner.IMPORT {
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P.Blank();
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} else {
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P.String(0, " = ");
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}
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P.Expr(d.val);
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}
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if d.list != nil {
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if d.tok != Scanner.FUNC {
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panic("must be a func declaration");
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}
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P.Blank();
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P.Block(d.list, true);
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}
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if d.tok != Scanner.TYPE {
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P.semi = true;
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}
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}
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P.newl = 1;
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// extra newline after a function declaration
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if d.tok == Scanner.FUNC {
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P.newl++;
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}
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// extra newline at the top level
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if P.level == 0 {
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P.newl++;
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}
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}
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// ----------------------------------------------------------------------------
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// Program
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func (P *Printer) Program(p *AST.Program) {
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// TODO should initialize all fields?
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P.clist = p.comments;
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P.cindex = 0;
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if p.comments.len() > 0 {
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P.cpos = p.comments.at(0).(*AST.Comment).pos;
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} else {
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P.cpos = 1000000000; // infinite
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}
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P.String(p.pos, "package ");
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P.Expr(p.ident);
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P.newl = 2;
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for i := 0; i < p.decls.len(); i++ {
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P.Declaration(p.decls.at(i), false);
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}
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P.newl = 1;
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P.String(0, ""); // flush
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}
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