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Copy pathparser.go
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549 lines (442 loc) · 8.74 KB
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package main
import (
"fmt"
"strconv"
)
type Parser struct {
tokens []Token
offset uint
}
func (p *Parser) peek() Token {
if len(p.tokens) == 0 {
panic("invalid argument, token input length 0")
}
if p.offset >= uint(len(p.tokens)) {
return p.tokens[len(p.tokens)-1]
}
return p.tokens[p.offset]
}
func (p *Parser) consume(kinds ...TokenKind) Token {
if len(p.tokens) == 0 {
panic("invalid argument, token input length 0")
}
if p.offset >= uint(len(p.tokens)) {
p.offset = uint(len(p.tokens)) - 1
}
var token = p.tokens[p.offset]
p.offset++
for _, kind := range kinds {
if token.kind == kind {
return token
}
}
var err = fmt.Errorf(
`Line %d: unexpected token "%s", expected any: %s`,
token.line,
token.lexeme,
kinds,
)
panic(err)
}
func getAst(tokens []Token) Ast {
if tokens == nil {
panic("null reference")
}
var parser Parser = Parser{tokens, 0}
return parseAst(&parser)
}
func parseAst(p *Parser) Ast {
var ast Ast
for {
switch p.peek().kind {
case FUN:
var f Func = parseFunc(p)
ast.funcs = append(ast.funcs, f)
case VAR:
var v Var = parseVar(p)
ast.vars = append(ast.vars, v)
default:
p.consume(EOF)
return ast
}
}
}
func parseVar(p *Parser) Var {
var v Var
p.consume(VAR)
v.name = p.consume(SYMBOL).lexeme
p.consume(COLON)
v.kind = parseType(p)
p.consume(EQUAL)
v.assigned = parseExpr(p)
return v
}
func parseType(p *Parser) Type {
switch p.consume(INT, STR, FUN, OBJ).kind {
case INT:
return TYPE_INT
case STR:
return TYPE_STR
case FUN:
return TYPE_FUN
case OBJ:
return TYPE_OBJ
default:
panic("invalid state")
}
}
func parseFunc(p *Parser) Func {
var f Func
p.consume(FUN)
f.name = p.consume(SYMBOL).lexeme
p.consume(LPAREN)
f.params = parseParams(p)
p.consume(RPAREN)
f.ret = parseReturnType(p)
p.consume(LBRACE)
f.body = parseStmts(p)
p.consume(RBRACE)
return f
}
func parseReturnType(p *Parser) Type {
if p.peek().kind != INT &&
p.peek().kind != STR &&
p.peek().kind != FUN &&
p.peek().kind != OBJ {
return TYPE_VOID
}
switch p.consume(INT, STR, FUN, OBJ).kind {
case INT:
return TYPE_INT
case STR:
return TYPE_STR
case FUN:
return TYPE_FUN
case OBJ:
return TYPE_OBJ
default:
panic("invalid state")
}
}
func parseParams(p *Parser) Params {
var params Params
for {
if p.peek().kind == ELLIPSIS {
p.consume(ELLIPSIS)
params.variadic = true
return params
}
if p.peek().kind != SYMBOL {
return params
}
params.vars = append(params.vars, parseParam(p))
if p.peek().kind == COMMA {
p.consume(COMMA)
}
}
}
func parseParam(p *Parser) Var {
var v Var
v.name = p.consume(SYMBOL).lexeme
p.consume(COLON)
v.kind = parseType(p)
p.consume(EQUAL)
v.assigned = parseExpr(p)
return v
}
func parseStmts(p *Parser) []Stmt {
var stmts []Stmt
for {
switch p.peek().kind {
case VAR:
stmts = append(stmts, StmtVar(parseVar(p)))
case IF:
stmts = append(stmts, parseIf(p))
case WHILE:
stmts = append(stmts, parseWhile(p))
case RETURN:
stmts = append(stmts, parseReturn(p))
case BREAK:
stmts = append(stmts, parseBreak(p))
case RBRACE:
return stmts
default:
stmts = append(stmts, parseStmtExpr(p))
}
}
}
func parseIf(p *Parser) StmtIf {
var stmt StmtIf
p.consume(IF)
stmt.test = parseExpr(p)
p.consume(LBRACE)
stmt.body = parseStmts(p)
p.consume(RBRACE)
stmt.elifs = parseStmtElif(p)
stmt.elseBody = parseStmtElse(p)
return stmt
}
func parseStmtElif(p *Parser) []StmtElif {
var stmts []StmtElif
for {
if p.peek().kind != ELIF {
return stmts
}
var stmt StmtElif
p.consume(ELIF)
stmt.test = parseExpr(p)
p.consume(LBRACE)
stmt.body = parseStmts(p)
p.consume(RBRACE)
stmts = append(stmts, stmt)
}
}
func parseStmtElse(p *Parser) []Stmt {
var stmts []Stmt
if p.peek().kind != ELSE {
return stmts
}
p.consume(ELSE)
p.consume(LBRACE)
stmts = parseStmts(p)
p.consume(RBRACE)
return stmts
}
func parseWhile(p *Parser) StmtWhile {
var stmt StmtWhile
p.consume(WHILE)
stmt.test = parseExpr(p)
p.consume(LBRACE)
stmt.body = parseStmts(p)
p.consume(RBRACE)
return stmt
}
func parseReturn(p *Parser) StmtReturn {
p.consume(RETURN)
return StmtReturn{parseExpr(p)}
}
func parseBreak(p *Parser) StmtBreak {
p.consume(BREAK)
return StmtBreak{}
}
func parseStmtExpr(p *Parser) StmtExpr {
return StmtExpr{parseExpr(p)}
}
func parseExpr(p *Parser) Expr {
return parseExprAssign(p)
}
func parseExprAssign(p *Parser) Expr {
var expr = parseExprLogic(p)
if p.peek().kind == EQUAL {
p.consume(EQUAL)
expr = ExprBinary{expr, parseExprAssign(p), OP_ASS}
}
return expr
}
func parseExprLogic(p *Parser) Expr {
var expr = parseExprCmp(p)
for p.peek().kind == AND || p.peek().kind == OR {
var op Op
if p.consume(AND, OR).kind == AND {
op = OP_AND
} else {
op = OP_OR
}
expr = ExprBinary{expr, parseExprCmp(p), op}
}
return expr
}
func parseExprCmp(p *Parser) Expr {
var expr = parseExprAdd(p)
for p.peek().kind == DOUBLE_EQUAL ||
p.peek().kind == NOT_EQUAL ||
p.peek().kind == LESSER_OR_EQUAL ||
p.peek().kind == GREATER_OR_EQUAL ||
p.peek().kind == LESSER_THAN ||
p.peek().kind == GREATER_THAN {
var op Op
switch p.consume(
DOUBLE_EQUAL,
NOT_EQUAL,
LESSER_OR_EQUAL,
GREATER_OR_EQUAL,
LESSER_THAN,
GREATER_THAN,
).kind {
case DOUBLE_EQUAL:
op = OP_EQ
case NOT_EQUAL:
op = OP_NEQ
case LESSER_OR_EQUAL:
op = OP_LE
case GREATER_OR_EQUAL:
op = OP_GE
case LESSER_THAN:
op = OP_LT
case GREATER_THAN:
op = OP_GT
default:
panic("invalid state")
}
expr = ExprBinary{expr, parseExprAdd(p), op}
}
return expr
}
func parseExprAdd(p *Parser) Expr {
var expr = parseExprMult(p)
for p.peek().kind == PLUS || p.peek().kind == MINUS {
var op Op
if p.consume(PLUS, MINUS).kind == PLUS {
op = OP_ADD
} else {
op = OP_SUB
}
expr = ExprBinary{expr, parseExprMult(p), op}
}
return expr
}
func parseExprMult(p *Parser) Expr {
var expr = parseExprUnary(p)
for p.peek().kind == STAR ||
p.peek().kind == SLASH ||
p.peek().kind == PERCENT {
var op Op
switch p.consume(STAR, SLASH, PERCENT).kind {
case STAR:
op = OP_MUL
case SLASH:
op = OP_DIV
case PERCENT:
op = OP_MOD
default:
panic("invalid state")
}
expr = ExprBinary{expr, parseExprUnary(p), op}
}
return expr
}
func parseExprUnary(p *Parser) Expr {
if p.peek().kind != PLUS &&
p.peek().kind != MINUS &&
p.peek().kind != BANG {
return parseExprPostfix(p)
}
var op Op
switch p.consume(PLUS, MINUS, BANG).kind {
case PLUS:
op = OP_ADD
case MINUS:
op = OP_SUB
case BANG:
op = OP_NOT
default:
panic("invalid state")
}
return ExprUnary{parseExprUnary(p), op}
}
func parseExprPostfix(p *Parser) Expr {
var expr = parseExprPrimary(p)
for {
if p.peek().kind == DOT {
p.consume(DOT)
var field = p.consume(SYMBOL).lexeme
expr = ExprField{expr, field}
} else if p.peek().kind == LPAREN {
p.consume(LPAREN)
var args = parseArgs(p)
p.consume(RPAREN)
expr = ExprCall{expr, args}
} else {
break
}
}
return expr
}
func parseArgs(p *Parser) []Expr {
var args []Expr
for {
if p.peek().kind == RPAREN {
return args
}
args = append(args, parseExpr(p))
if p.peek().kind == COMMA {
p.consume(COMMA)
}
}
}
func parseExprPrimary(p *Parser) Expr {
var expr Expr
if p.peek().kind == LPAREN {
p.consume(LPAREN)
expr = parseExpr(p)
p.consume(RPAREN)
} else {
expr = parseValue(p)
}
return expr
}
func parseValue(p *Parser) Expr {
switch p.peek().kind {
case NUMBER:
return parseExprNumber(p)
case STRING:
return parseExprString(p)
case SYMBOL:
return parseExprSymbol(p)
case OBJ:
return parseExprObj(p)
case NIL:
return parseExprNil(p)
default:
return ExprNil{}
}
}
func parseExprNumber(p *Parser) ExprNumber {
var expr ExprNumber
var numText = p.consume(NUMBER).lexeme
var number, err = strconv.ParseInt(numText, 10, 64)
if err != nil {
panic(fmt.Sprintf("%s too big (max 9223372036854775807)",
numText))
}
expr.value = number
return expr
}
func parseExprString(p *Parser) ExprString {
var expr ExprString
var str = p.consume(STRING).lexeme
var unqoted, _ = strconv.Unquote(str)
expr.value = unqoted
return expr
}
func parseExprSymbol(p *Parser) ExprSymbol {
return ExprSymbol{p.consume(SYMBOL).lexeme}
}
func parseExprObj(p *Parser) ExprObject {
var obj ExprObject
p.consume(OBJ)
p.consume(LBRACE)
var vars []Var
for {
if p.peek().kind != SYMBOL {
break
}
var v Var
v.name = p.consume(SYMBOL).lexeme
p.consume(COLON)
v.kind = parseType(p)
p.consume(EQUAL)
v.assigned = parseExpr(p)
vars = append(vars, v)
if p.peek().kind == COMMA {
p.consume(COMMA)
}
}
obj.fields = vars
p.consume(RBRACE)
return obj
}
func parseExprNil(p *Parser) ExprNil {
p.consume(NIL)
return ExprNil{}
}
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