feat(sexpr): add ParseError

thi-ng · Sep 12, 2019 · 7998afe · 7998afe
1 parent 1c152d3
commit 7998afe
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/packages/sexpr/package.json b/packages/sexpr/package.json
@@ -34,7 +34,8 @@
     },
     "dependencies": {
         "@thi.ng/api": "^6.3.3",
-        "@thi.ng/defmulti": "1.1.3"
+        "@thi.ng/defmulti": "1.1.3",
+        "@thi.ng/errors": "1.2.0"
     },
     "keywords": [
         "DSL",

diff --git a/packages/sexpr/src/parse.ts b/packages/sexpr/src/parse.ts
@@ -1,4 +1,4 @@
-import { assert } from "@thi.ng/api";
+import { defError } from "@thi.ng/errors";
 import {
     DEFAULT_SYNTAX,
     Expression,
@@ -7,6 +7,8 @@ import {
     SyntaxOpts
 } from "./api";
 
+const ParseError = defError<string>((msg?) => msg || "Parser error", () => "");
+
 export const parse = (tokens: Iterable<string>, opts?: Partial<SyntaxOpts>) => {
     const { scopeOpen, scopeClose } = {
         ...DEFAULT_SYNTAX,
@@ -18,7 +20,9 @@ export const parse = (tokens: Iterable<string>, opts?: Partial<SyntaxOpts>) => {
             tree.push({ type: "expr", value: t, children: [] });
         } else if (scopeClose.indexOf(t) !== -1) {
             // TODO check matching scope type
-            assert(tree.length > 1, "invalid nesting");
+            if (tree.length < 2) {
+                throw new ParseError(`unmatched '${t}'`);
+            }
             (<Expression>tree[tree.length - 2]).children!.push(tree.pop()!);
         } else {
             let node: Node;
@@ -37,5 +41,8 @@ export const parse = (tokens: Iterable<string>, opts?: Partial<SyntaxOpts>) => {
             (<Expression>tree[tree.length - 1]).children!.push(node);
         }
     }
+    if (tree.length > 1) {
+        throw new ParseError("invalid s-expression");
+    }
     return <RootNode>tree[0];
 };