Breaking: support path expressions instead of level.

CHANGELOG.md

@@ -0,0 +1,3 @@
+# 0.3.0
+
+Breaking: support path expressions instead of level.

README.md

@@ -11,13 +11,13 @@ A high-level wrapper over [JsonHilo](https://github.com/xtao-org/jsonhilo) which
 ```js
 // see also quickstart.js
 // replace vx.y.z below with latest/desired version
-import {JsonStrum} from 'https://cdn.jsdelivr.net/gh/xtao-org/jsonstrum@v0.2.0/mod.js'
+import {JsonStrum} from 'https://cdn.jsdelivr.net/gh/xtao-org/jsonstrum@v0.3.0/mod.js'
 
 const s = JsonStrum({
   object: (object) => console.log('object', object),
   array: (array) => console.log('array', array),
-  // will only parse and emit objects at this level of nesting 
-  level: 1,
+  // will only parse and emit objects at given path
+  path: [{}, {}]
 })
 
 s.push(`

mod.js

@@ -1,69 +1,141 @@
 import { JsonHigh } from "./deps.js"
 
+// todo: recursive descent, e.g. [{}, "x", {depthRange: []}, "obj"]
+// depthRange: [0, 3] would be the same as ...([] | [{}] | [{}, {}] | [{}, {}, {}])
+// depthRange: [] would be unbounded
+
+// could also abstract the matcher into a module
+const matchPath = (path, expr) => {
+  // perhaps this should only check if prefix of path matches
+  // i.e. it's enough that path.length >= expr.length
+  // or maybe there should be a flag parameter which determines whether the match should be exact or just prefix
+  if (path.length !== expr.length) return false
+  for (let i = 0; i < expr.length; ++i) {
+    const e = expr[i]
+    const p = path[i]
+
+    if (e === p) continue
+    if (Array.isArray(e)) {
+      if (e.length === 0) throw Error('empty alternative')
+      for (const k of e) {
+        if (p === k) continue
+      }
+      return false
+    }
+    // todo:
+    // assume object
+    const {range, regex} = e
+    if (range !== undefined) {
+      if (regex !== undefined) throw Error(`can't have regex & range simultaneously`)
+      // assume no more than 2 elements
+      // could also support step to match every nth element
+      const [from, to] = e
+      if (from !== undefined) {
+        if (p < from) return false
+      }
+      if (to !== undefined) {
+        if (p > to) return false
+      }
+    }
+    if (regex !== undefined) {
+      // assume match is a regex
+      if (regex.test(p)) continue
+      // throw Error(`must have either match or range`)
+    }
+    // assume empty object
+    continue
+  }
+  return true
+}
+
+// perhaps this should also support non-object values (primitives)
 export const JsonStrum = ({
   object,
   array,
-  level = 0
+  // perhaps rename to query or pathQuery or pathExpr
+  path = [{}],
 } = {}) => {
   const ancestors = []
   let parent = null
   let current = null
-  let key = null
   let currentLevel = 0
+  const currentPath = [-1]
+  const level = path.length - 1
 
   const close = () => {
     --currentLevel
-    if (currentLevel === level) {
+    currentPath.pop()
+    // if currentPath matches exactly
+    if (currentLevel === level && matchPath(currentPath, path)) {
       if (Array.isArray(current)) {
-        array?.(current)
+        array?.(current, currentPath)
       } else {
-        object?.(current)
+        object?.(current, currentPath)
       }
       current = null
       parent = null
+    // if a prefix of currentPath matches
     } else if (currentLevel > level) {
       if (Array.isArray(parent)) {
         parent.push(current)
       } else {
-        parent[key] = current
+        parent[currentPath.at(-1)] = current
       }
       current = parent
       parent = ancestors.pop()
     }
   }
 
+  const incrementIndex = () => {
+    const last = currentPath.at(-1)
+    if (typeof last === 'number') {
+      currentPath[currentPath.length - 1] += 1
+    }
+  }
+
   return JsonHigh({
     openArray: () => {
       ++currentLevel
-      if (currentLevel > level) {
+      // if a prefix of current path matches
+      if (currentLevel > level && matchPath(currentPath.slice(0, path.length), path)) {
         if (current !== null) {
           ancestors.push(parent)
           parent = current
         }
         current = []
       }
+      incrementIndex()
+      currentPath.push(-1)
     },
     openObject: () => {
       ++currentLevel
-      if (currentLevel > level) {
+      // if a prefix of current path matches
+      if (currentLevel > level && matchPath(currentPath.slice(0, path.length), path)) {
         if (current !== null) {
           ancestors.push(parent)
           parent = current
         }
         current = {}
       }
+      incrementIndex()
+      currentPath.push("")
     },
     closeArray: close,
     closeObject: close,
-    key: (k) => { if (currentLevel > level) key = k },
+    key: (k) => { 
+      // if (currentLevel > level && matchPath(currentPath.slice(0, path.length), path)) key = k
+      currentPath[currentPath.length - 1] = k
+    },
     value: (value) => {
-      if (currentLevel > level) {
+      // if a prefix of current path matches
+      if (currentLevel > level && matchPath(currentPath.slice(0, path.length), path)) {
         if (Array.isArray(current)) {
           current.push(value)
         } else {
-          current[key] = value
+          current[currentPath.at(-1)] = value
         }
       }
+      incrementIndex()
     },
   })
 }

quickstart.js

@@ -1,9 +1,9 @@
-import {JsonStrum} from 'https://cdn.jsdelivr.net/gh/xtao-org/[email protected]/mod.js'
+import {JsonStrum} from './mod.js'
 
 const s = JsonStrum({
-  object: (object) => console.log('object', object),
-  array: (array) => console.log('array', array),
-  level: 1,
+  object: (object, p) => console.log('object', object, p),
+  array: (array, p) => console.log('array', array, p),
+  path: [{}, {}],
 })
 
 s.push(`

test.js

@@ -1,8 +1,9 @@
 import {JsonStrum} from './mod.js'
 
 const s = JsonStrum({
-  object: (object) => console.log('object', object),
-  array: (array) => console.log('array', array),
+  object: (object, p) => console.log('object', object, p),
+  array: (array, p) => console.log('array', array, p),
+  path: [{}, "sub"]
 })
 
 s.push(`
@@ -19,9 +20,9 @@ s.push(`,
 [1, 2, 3]`)
 
 const s2 = JsonStrum({
-  object: (object) => console.log('object', object),
-  array: (array) => console.log('array', array),
-  level: 1,
+  object: (object, p) => console.log('object', object, p),
+  array: (array, p) => console.log('array', array, p),
+  path: [{}, {}]
 })
 
 s2.push(`[
@@ -37,9 +38,9 @@ s2.push(`[
 
 
 const s3 = JsonStrum({
-  object: (object) => console.log('object', object),
-  array: (array) => console.log('array', array),
-  level: 3,
+  object: (object, p) => console.log('object', object, p),
+  array: (array, p) => console.log('array', array, p),
+  path: [{}, {}, {}, {}]
 })
 
 s3.push(`