Added alternate expression parser.

This adds an alternate expression parser designed solely for arithmetic
operations.

1 files changed, 54 insertions, 0 deletions

diff --git a/dice-lang/src/bjc/dicelang/expr/Lexer.java b/dice-lang/src/bjc/dicelang/expr/Lexer.java
new file mode 100644
index 0000000..cff1170
--- /dev/null
+++ b/dice-lang/src/bjc/dicelang/expr/Lexer.java
@@ -0,0 +1,54 @@
+package bjc.dicelang.expr;
+
+import bjc.utils.funcutils.TokenSplitter;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Implements the lexer for simple expression operations.
+ *
+ * @author Ben Culkin
+ */
+public class Lexer {
+	/*
+	 * Spliter we use
+	 */
+	private TokenSplitter split;
+
+	/**
+	 * Create a new expression lexer.
+	 */
+	public Lexer() {
+		split = new TokenSplitter();
+
+		split.addDelimiter("(", ")");
+		split.addDelimiter("+", "-", "*", "/");
+	}
+
+	/**
+	 * Convert a string from a input command to a series of infix tokens.
+	 *
+	 * @param inp
+	 *                The input command.
+	 * @param tks
+	 *                The token state
+	 *
+	 * @return A series of infix tokens representing the command.
+	 */
+	public Token[] lexString(String inp, Tokens tks) {
+		String[] spacedTokens = inp.split("[ \t]");
+
+		List<Token> tokens = new LinkedList<>();
+
+		for(String spacedToken : spacedTokens) {
+			String[] rawTokens = split.split(spacedToken);
+
+			for(String tok : rawTokens) {
+				tokens.add(tks.lexToken(tok, spacedToken));
+			}
+		}
+
+		return tokens.toArray(new Token[0]);
+	}
+}