fix(lexer): handle unary minus operator (#262)

* fix(lexer): handle unary minus operator add tests for lexer * avoid duplication of top value --------- Co-authored-by: Jeremy Valentine <[email protected]>
javalent · Oct 26, 2023 · 139cbfa · 139cbfa
1 parent 0f2c599
commit 139cbfa
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Showing 4 changed files with 446 additions and 12 deletions.
diff --git a/src/parser/lexer.ts b/src/parser/lexer.ts
@@ -4,6 +4,7 @@ import * as moo from "moo";
 import DiceRollerPlugin from "src/main";
 import { Conditional } from "src/types";
 import { Parser } from "./parser";
+import copy from "fast-copy";
 
 export const TAG_REGEX =
     /(?:\d+[Dd])?#(?:[\p{Letter}\p{Emoji_Presentation}\w/-]+)(?:\|(?:[+-]))?(?:\|(?:[^+-]+))?/u;
@@ -133,7 +134,7 @@ export default class Lexer {
             "^": exponent
         });
     }
-    parse(input: string) {
+    parse(input: string): LexicalToken[] {
         const tokens = Array.from(this.lexer.reset(input));
         this.lexer.reset();
         return this.parser.parse(this.transform(tokens));
@@ -142,18 +143,37 @@ export default class Lexer {
         tokens = tokens.filter((token) => {
             return token.type != "WS";
         });
-        let clone: LexicalToken[] = [];
-        /** If the first token is a negative sign and the second is a dice roller, just make the dice roller negative. */
-        if (tokens.length >= 2) {
-            if (
-                (tokens[0].type === "-" ||
-                    (tokens[0].type === "math" && tokens[0].value === "-")) &&
-                tokens[1].type === "dice"
-            ) {
-                tokens[1].value = `-${tokens[1].value}`;
-                tokens.shift();
+
+        let isPlus = (t: moo.Token) =>
+            t.type === "+" || (t.type === "math" && t.value === "+");
+        let isMinus = (t: moo.Token) =>
+            t.type === "-" || (t.type === "math" && t.value === "-");
+        let isPlusOrMinus = (t: moo.Token) => isPlus(t) || isMinus(t);
+        let peek = (arr: moo.Token[]) => arr[arr.length - 1];
+        let replaceTop = (arr: moo.Token[], newTop: moo.Token) =>
+            arr.splice(arr.length - 1, 1, newTop);
+
+        tokens = tokens.reduce((acc, e) => {
+            if (acc.length == 0) {
+                acc.push(e);
+            } else {
+                let top = peek(acc);
+
+                if (isPlusOrMinus(top) && isPlusOrMinus(e)) {
+                    if (isMinus(top) != isMinus(e)) {
+                        // one minus => minus
+                        if (!isMinus(top)) replaceTop(acc, e);
+                    } else if (isMinus(top)) {
+                        top.type = top.type === "math" ? top.type : "+";
+                        top.value = "+";
+                    }
+                } else {
+                    acc.push(e);
+                }
             }
-        }
+            return acc;
+        }, [] as moo.Token[]);
+        let clone: LexicalToken[] = [];
         for (const token of tokens) {
             if (token.type == "condition" && clone.length > 0) {
                 const previous = clone[clone.length - 1];