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Diffstat (limited to 'JPratt/src/main/java/bjc/utils/parserutils/pratt/commands/TernaryCommand.java')
| -rw-r--r-- | JPratt/src/main/java/bjc/utils/parserutils/pratt/commands/TernaryCommand.java | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/JPratt/src/main/java/bjc/utils/parserutils/pratt/commands/TernaryCommand.java b/JPratt/src/main/java/bjc/utils/parserutils/pratt/commands/TernaryCommand.java new file mode 100644 index 0000000..8f04368 --- /dev/null +++ b/JPratt/src/main/java/bjc/utils/parserutils/pratt/commands/TernaryCommand.java @@ -0,0 +1,77 @@ +package bjc.utils.parserutils.pratt.commands; + +import bjc.utils.data.ITree; +import bjc.utils.data.Tree; +import bjc.utils.parserutils.ParserException; +import bjc.utils.parserutils.pratt.ParseBlock; +import bjc.utils.parserutils.pratt.ParserContext; +import bjc.utils.parserutils.pratt.Token; + +/** + * A ternary command, like C's ?: + * + * @author bjculkin + * + * @param <K> + * The key type of the tokens. + * + * @param <V> + * The value type of the tokens. + * + * @param <C> + * The state type of the parser. + */ +public class TernaryCommand<K, V, C> extends BinaryPostCommand<K, V, C> { + private ParseBlock<K, V, C> innerBlck; + + private Token<K, V> mark; + + private boolean nonassoc; + + /** + * Create a new ternary command. + * + * @param precedence + * The precedence of this operator. + * + * @param innerBlock + * The representation of the inner block of the + * expression. + * + * @param marker + * The token to use as the root of the AST node. + * + * @param isNonassoc + * Whether or not the conditional is associative. + */ + public TernaryCommand(int precedence, ParseBlock<K, V, C> innerBlock, Token<K, V> marker, boolean isNonassoc) { + super(precedence); + + if (innerBlock == null) + throw new NullPointerException("Inner block must not be null"); + else if (marker == null) throw new NullPointerException("Marker must not be null"); + + innerBlck = innerBlock; + mark = marker; + nonassoc = isNonassoc; + } + + @Override + public ITree<Token<K, V>> denote(ITree<Token<K, V>> operand, Token<K, V> operator, ParserContext<K, V, C> ctx) + throws ParserException { + ITree<Token<K, V>> inner = innerBlck.parse(ctx); + + ITree<Token<K, V>> outer = ctx.parse.parseExpression(1 + leftBinding(), ctx.tokens, ctx.state, false); + + return new Tree<>(mark, inner, operand, outer); + } + + @Override + public int nextBinding() { + if (nonassoc) { + return leftBinding() - 1; + } else { + return leftBinding(); + } + } +}
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