Initial commit

json.js

@@ -0,0 +1,143 @@
+
+
+
+function jsonQuery(json, path, defaultValue = null) {
+
+    let toks = tokenizePath(path);
+    let ptr = json;
+    let search = null;
+    let searchTok = null;
+    let multiResult = null;
+
+    let tok;
+    while (tok = toks.shift()) {
+        switch (tok) {
+            case ".": // find key
+                search = 'key';
+                break;
+            case "[": // find array index
+                search = "array";
+                break;
+            case "]": // find 
+                // if searchTok is "", match all items
+                if (search !== "array") {
+                    throw new Error("Invalid path");
+                }
+                if (searchTok === null) {
+                    if (multiResult !== null) {
+                        throw new Error("Can't match full arrays on multiple levels");
+                    }
+                    multiResult = [];
+                    ptr.forEach(item => {
+                        let res = jsonQuery(item, toks.join(""));
+                        multiResult.push(res);
+                    });
+                    return multiResult;
+                }
+                if (typeof ptr[searchTok] === 'undefined') {
+                    return defaultValue;
+                }
+                ptr = ptr[searchTok];
+                break;
+            default:
+                if (search === 'key') {
+                    // find key tok in ptr
+                    if (typeof ptr[tok] === 'undefined') {
+                        return defaultValue;
+                    } else {
+                        ptr = ptr[tok];
+                    }
+                } else if (search  === 'array') {
+                    // find index tok in ptr after finding a ]
+                    searchTok = tok;
+                }
+        }
+    }
+    return ptr;
+}
+
+function jsonPatch(json, path, value) {
+    let toks = tokenizePath(path);
+    json = structuredClone(json);
+    let ptr = json;
+    let search = null;
+    let searchTok = null;
+    let multiResult = null;
+
+    let tok;
+    while (tok = toks.shift()) {
+        switch (tok) {
+            case ".": // find key
+                search = 'key';
+                break;
+            case "[": // find array index
+                search = "array";
+                break;
+            case "]": // find 
+                // if searchTok is "", match all items
+                if (search !== "array") {
+                    throw new Error("Invalid path");
+                }
+                if (searchTok === null) {
+                    throw new Error("Can't patch arrays yet");
+                }
+                if (typeof ptr[searchTok] === 'undefined') {
+                    return json;
+                }
+                ptr = ptr[searchTok];
+                break;
+            default:
+                if (search === 'key') {
+                    // find key tok in ptr
+                    if (typeof ptr[tok] === 'undefined') {
+                        return defaultValue;
+                    } else {
+                        if (toks.length === 0) {
+                            ptr[tok] = value;
+                            return json;
+                        } else {
+                            ptr = ptr[tok];
+                        }
+                    }
+                } else if (search  === 'array') {
+                    // find index tok in ptr after finding a ]
+                    searchTok = tok;
+                }
+        }
+    }
+    // ptr = value;
+
+    return json;
+}
+
+function tokenizePath(path) {
+    let t = [];
+    let b = null;
+    for (let p = 0; p < path.length; p++) {
+        let c = path[p];
+        if (c == ".") {
+            if (b !== null) t.push(b);
+            b = null;
+            t.push(".");
+        } else if (c == "[") {
+            if (b !== null) t.push(b);
+            b = null;
+            t.push("[");
+        } else if (c == "]") {
+            if (b !== null) t.push(b);
+            b = null;
+            t.push("]");
+        } else {
+            b = ((b===null)?"":b) + c;
+        }
+    }
+    if (b !== null) t.push(b);
+    return t;
+}
+
+
+export {
+    tokenizePath,
+    jsonQuery,
+    jsonPatch,
+};