diff options
Diffstat (limited to 'parser/parse.go')
| -rw-r--r-- | parser/parse.go | 83 |
1 files changed, 52 insertions, 31 deletions
diff --git a/parser/parse.go b/parser/parse.go index 901ac7d..4ccb151 100644 --- a/parser/parse.go +++ b/parser/parse.go @@ -13,11 +13,13 @@ import ( type Parser struct { *scanner.Scanner - symbols map[string]*symbol - function *symbol - scope string - fname string + symbols map[string]*symbol + function *symbol + scope string + fname string + labelCount map[string]int + breakLabel string } func (p *Parser) Scan(s string, endSemi bool) (Tokens, error) { @@ -77,7 +79,6 @@ func (p *Parser) Parse(src string) (out Tokens, err error) { // Skip over simple init statements for some tokens (if, for, ...) if lang.HasInit[in[0].Id] { - log.Println("may have init") for in[endstmt-1].Id != lang.BraceBlock { e2 := in[endstmt+1:].Index(lang.Semicolon) if e2 == -1 { @@ -102,6 +103,8 @@ func (p *Parser) ParseStmt(in Tokens) (out Tokens, err error) { return nil, nil } switch t := in[0]; t.Id { + case lang.Break: + return p.ParseBreak(in) case lang.For: return p.ParseFor(in) case lang.Func: @@ -115,11 +118,27 @@ func (p *Parser) ParseStmt(in Tokens) (out Tokens, err error) { } } +func (p *Parser) ParseBreak(in Tokens) (out Tokens, err error) { + var label string + switch len(in) { + case 1: + label = p.breakLabel + case 2: + if in[1].Id != lang.Ident { + return nil, fmt.Errorf("invalid break statement") + } + label = in[1].Str + default: + return nil, fmt.Errorf("invalid break statement") + } + out = Tokens{{Id: lang.Goto, Str: "goto " + label}} + return out, err +} + func (p *Parser) ParseFor(in Tokens) (out Tokens, err error) { // TODO: detect invalid code. - fc := strconv.Itoa(p.labelCount[p.scope+p.fname]) - prefix := p.fname + "_for" + fc - p.labelCount[p.scope+p.fname]++ + fc := strconv.Itoa(p.labelCount[p.scope]) + p.labelCount[p.scope]++ var init, cond, post, body Tokens pre := in[1 : len(in)-1].Split(lang.Semicolon) switch len(pre) { @@ -131,20 +150,25 @@ func (p *Parser) ParseFor(in Tokens) (out Tokens, err error) { return nil, fmt.Errorf("invalild for statement") } p.pushScope("for" + fc) - defer p.popScope() + breakLabel := p.breakLabel + p.breakLabel = p.scope + "e" + defer func() { + p.breakLabel = breakLabel + p.popScope() + }() if len(init) > 0 { if init, err = p.ParseStmt(init); err != nil { return nil, err } out = init } - out = append(out, scanner.Token{Id: lang.Label, Str: prefix + "b"}) + out = append(out, scanner.Token{Id: lang.Label, Str: p.scope + "b"}) if len(cond) > 0 { if cond, err = p.ParseExpr(cond); err != nil { return nil, err } out = append(out, cond...) - out = append(out, scanner.Token{Id: lang.JumpFalse, Str: "JumpFalse " + prefix + "e"}) + out = append(out, scanner.Token{Id: lang.JumpFalse, Str: "JumpFalse " + p.scope + "e"}) } if body, err = p.Parse(in[len(in)-1].Block()); err != nil { return nil, err @@ -157,8 +181,8 @@ func (p *Parser) ParseFor(in Tokens) (out Tokens, err error) { out = append(out, post...) } out = append(out, - scanner.Token{Id: lang.Goto, Str: "goto " + prefix + "b"}, - scanner.Token{Id: lang.Label, Str: prefix + "e"}) + scanner.Token{Id: lang.Goto, Str: "goto " + p.scope + "b"}, + scanner.Token{Id: lang.Label, Str: p.scope + "e"}) return out, err } @@ -216,14 +240,14 @@ func (p *Parser) ParseFunc(in Tokens) (out Tokens, err error) { } func (p *Parser) ParseIf(in Tokens) (out Tokens, err error) { - prefix := p.fname + "_if" + strconv.Itoa(p.labelCount[p.scope+p.fname]) - p.labelCount[p.scope+p.fname]++ - sc := 0 - ssc := strconv.Itoa(sc) + label := "if" + strconv.Itoa(p.labelCount[p.scope]) + p.labelCount[p.scope]++ + p.pushScope(label) + defer p.popScope() // We start from the end of the statement and examine tokens backward to // get the destination labels already computed when jumps are set. - i := len(in) - 1 - for i > 0 { + for sc, i := 0, len(in)-1; i > 0; sc++ { + ssc := strconv.Itoa(sc) if in[i].Id != lang.BraceBlock { return nil, fmt.Errorf("expected '{', got %v", in[i]) } @@ -232,21 +256,19 @@ func (p *Parser) ParseIf(in Tokens) (out Tokens, err error) { return nil, err } if sc > 0 { - pre = append(pre, scanner.Token{Id: lang.Goto, Str: "goto " + prefix + "_e0"}) + pre = append(pre, scanner.Token{Id: lang.Goto, Str: "goto " + p.scope + "e0"}) } - pre = append(pre, scanner.Token{Id: lang.Label, Str: prefix + "_e" + ssc}) + pre = append(pre, scanner.Token{Id: lang.Label, Str: p.scope + "e" + ssc}) out = append(pre, out...) i-- - ifp := in[:i].LastIndex(lang.If) if in[i].Id == lang.Else { // Step over final 'else'. i-- - sc++ - ssc = strconv.Itoa(sc) continue } pre = Tokens{} var init, cond Tokens + ifp := in[:i].LastIndex(lang.If) initcond := in[ifp+1 : i+1] if ii := initcond.Index(lang.Semicolon); ii < 0 { cond = initcond @@ -264,14 +286,12 @@ func (p *Parser) ParseIf(in Tokens) (out Tokens, err error) { return nil, err } pre = append(pre, cond...) - pre = append(pre, scanner.Token{Id: lang.JumpFalse, Str: "JumpFalse " + prefix + "_e" + ssc}) + pre = append(pre, scanner.Token{Id: lang.JumpFalse, Str: "JumpFalse " + p.scope + "e" + ssc}) out = append(pre, out...) i = ifp if i > 1 && in[i].Id == lang.If && in[i-1].Id == lang.Else { // Step over 'else if'. i -= 2 } - sc++ - ssc = strconv.Itoa(sc) } return out, err } @@ -403,15 +423,16 @@ func (p *Parser) numItems(s string, sep lang.TokenId) int { } func (p *Parser) pushScope(name string) { - p.scope = strings.TrimPrefix(p.scope+"/"+name+"/", "/") + if p.scope != "" { + p.scope += "/" + } + p.scope += name } func (p *Parser) popScope() { - p.scope = strings.TrimSuffix(p.scope, "/") j := strings.LastIndex(p.scope, "/") if j == -1 { - p.scope = "" - return + j = 0 } p.scope = p.scope[:j] } |