func parseBinaryExpr(p *Parser, tree ast.Expr, last *ast.BinaryExpr) ast.Expr {
if last.Y == nil {
switch t := p.nextNonNewline(); {
case isUnaryOp(t):
unary := &ast.UnaryExpr{Op: t}
tree, _ = ast.InsertExpr(tree, unary)
return parseUnaryExpr(p, tree, unary)
case t.Typ == lex.IDENTIFIER:
ident := newIdentExpr(p, t)
tree, _ = ast.InsertExpr(tree, ident)
return parseLiteralOrIdent(p, tree, ident)
case isLiteral(t):
bLit := &ast.BasicLit{Tok: t}
tree, _ = ast.InsertExpr(tree, bLit)
return parseLiteralOrIdent(p, tree, bLit)
case t.Typ == lex.LEFTPAREN:
paren := newParenExpr(p, t)
tree, _ = ast.InsertExpr(tree, paren)
return parseParenExpr(p, tree, paren)
default:
p.errorf("Invalid expression at line %d:%d with token '%s' in file : %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
}
} else {
p.errorf("Internal Error: Invalid parser state in parseBinaryExpr")
return nil
}
return nil
}
func parseLiteralOrIdent(p *Parser, tree, last ast.Expr) ast.Expr {
switch t := p.next(); {
case t.IsOperator():
oper := &ast.BinaryExpr{Op: t}
tree, _ = ast.InsertExpr(tree, oper)
return parseBinaryExpr(p, tree, oper)
case t.Typ == lex.NEWLINE && len(p.pDepth.Stack) > 0:
return parseLiteralOrIdent(p, tree, last)
case atTerminator(t):
return tree
case t.Typ == lex.RIGHTPAREN:
paren := p.pDepth.pop()
paren.Rparen = t
return parseParenExpr(p, tree, paren)
default:
p.errorf("Invalid expression at line %d:%d with token '%s' in file : %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
}
return nil
}
func parseParenExpr(p *Parser, tree ast.Expr, last *ast.ParenExpr) ast.Expr {
// if expr.X == nil && expr.Rparen.Val == ""
// else if expr.X != nil && expr.Rparen.Val == ""
// else if expr.Rparen.Val == ")"
// Unclosed Empty paren expr
if last.X == nil && last.Rparen.Val == "" {
switch t := p.nextNonNewline(); {
case t.Typ == lex.IDENTIFIER:
ident := newIdentExpr(p, t)
tree, _ = ast.InsertExpr(tree, ident)
return parseLiteralOrIdent(p, tree, ident)
case isLiteral(t):
num := &ast.BasicLit{Tok: t}
tree, _ = ast.InsertExpr(tree, num)
return parseLiteralOrIdent(p, tree, num)
case isUnaryOp(t):
unary := &ast.UnaryExpr{Op: t}
tree, _ = ast.InsertExpr(tree, unary)
return parseUnaryExpr(p, tree, unary)
case t.Typ == lex.LEFTPAREN:
paren := newParenExpr(p, t)
tree, _ = ast.InsertExpr(tree, paren)
return parseParenExpr(p, tree, paren)
case t.Typ == lex.RIGHTPAREN:
paren := p.pDepth.pop()
paren.Rparen = t
if paren != last {
p.errorf("Internal error in parseLiteralOrIdent closing paren not matching current paren expr at line %d:%d with token '%s' in file : %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
}
return parseParenExpr(p, tree, last)
default:
p.errorf("Invalid expression at line %d:%d with token '%s' in file %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
}
} else if last.Rparen.Val == ")" {
if last.X == nil {
// empty closed paren expr ()
// give value nil to ()
fmt.Printf("Warning: empty paren expression has value nil")
}
// Closed non-empty paren expr
switch t := p.next(); {
case t.IsOperator():
binary := &ast.BinaryExpr{Op: t}
tree, _ = ast.InsertExpr(tree, binary)
return parseBinaryExpr(p, tree, binary)
case t.Typ == lex.LEFTPAREN:
p.errorf("Invalid paren expression closed expression followed by opening parenthesis at line %d:%d with token '%s' in file %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
return nil
case t.Typ == lex.RIGHTPAREN:
// close enclosing paren in case parenExpr{X:parenExpr{}}
paren := p.pDepth.pop()
paren.Rparen = t
return parseParenExpr(p, tree, paren)
case t.Typ == lex.NEWLINE && len(p.pDepth.Stack) > 0:
return parseParenExpr(p, tree, last)
case atTerminator(t):
return tree
default:
p.errorf("Invalid paren expression at line %d:%d with token '%s' in file : %s\n", p.lineNumber(), t.Pos, t.Val, p.name)
}
} else {
p.errorf("Internal error in parseParenExpr: at line %d:%d with token '%s' in file: %s\n", p.lineNumber(), p.lastToken.Pos, p.lastToken.Val, p.name)
return nil
}
return nil
}