65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package saccharine
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import (
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"fmt"
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"unicode"
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"git.maximhutz.com/max/lambda/pkg/iterator"
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"git.maximhutz.com/max/lambda/pkg/token"
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)
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// Pulls the next token from an iterator over runes. If it cannot, it will
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// return nil. If an error occurs, it will return that.
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func scanToken(i *iterator.Iterator[rune]) (*Token, error) {
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index := i.Index()
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if i.Done() {
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return nil, nil
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}
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letter, err := i.Next()
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if err != nil {
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return nil, fmt.Errorf("cannot produce next token: %w", err)
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}
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switch {
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case letter == '(':
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return token.New(TokenOpenParen, index), nil
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case letter == ')':
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return token.New(TokenCloseParen, index), nil
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case letter == '.':
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return token.New(TokenDot, index), nil
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case letter == '\\':
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return token.New(TokenSlash, index), nil
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case letter == '\n':
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return token.New(TokenSoftBreak, index), nil
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case letter == '{':
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return token.New(TokenOpenBrace, index), nil
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case letter == '}':
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return token.New(TokenCloseBrace, index), nil
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case letter == ':':
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if _, err := token.ScanCharacter(i, '='); err != nil {
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return nil, err
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} else {
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return token.New(TokenAssign, index), nil
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}
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case letter == ';':
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return token.New(TokenHardBreak, index), nil
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case letter == '#':
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// Skip everything until the next newline or EOF.
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i.While(func(r rune) bool { return r != '\n' })
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return nil, nil
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case unicode.IsSpace(letter):
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return nil, nil
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case token.IsVariable(letter):
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return token.ScanAtom(i, letter, TokenAtom, index), nil
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}
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return nil, fmt.Errorf("unknown character '%v'", string(letter))
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}
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// scan a string into tokens.
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func scan(input string) ([]Token, error) {
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return token.Scan(input, scanToken)
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}
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