Refactor const, let, assignment

allow multiple const decls and multiple assignments

src/ast_utils.js

@@ -13,9 +13,11 @@ export const collect_destructuring_identifiers = node => {
     ['array_destructuring', 'object_destructuring', 'function_args']
       .includes(node.type)
   ) {
-    return node.elements
+    return node.children
         .map(collect_destructuring_identifiers)
         .flat()
+  } else if (node.type == 'decl_pair') {
+    return collect_destructuring_identifiers(node.children[0])
   } else {
     console.error(node)
     throw new Error('not implemented')

src/cmd.js

@@ -539,7 +539,9 @@ const goto_definition = (state, index) => {
             if(n.is_default && d.is_default) {
               return n.children[0]
             } else if(!n.is_default && !d.is_default) {
-              const ids = collect_destructuring_identifiers(n.binding.name_node)
+              const ids = n.binding.children.flatMap(c => 
+                collect_destructuring_identifiers(c.name_node)
+              )
               return ids.find(i => i.value == node.value)
             }
           })
@@ -592,6 +594,71 @@ const filter_calltree = (calltree, pred) => {
 }
 */
 
+const get_stmt_value_explorer = (state, stmt) => {
+  if(stmt.result == null) {
+    // statement was not evaluated
+    return null
+  }
+
+  let result
+
+  if(stmt.result.ok) {
+    if(stmt.type == 'return') {
+      result = stmt.children[0].result
+    } else if(['let', 'const', 'assignment'].includes(stmt.type)) {
+      const identifiers = stmt
+        .children
+        .flatMap(
+          collect_destructuring_identifiers
+        )
+        .filter(id => id.result != null)
+        .map(id => [id.value, id.result.value])
+      let value
+      if(
+        stmt.children.length == 1 
+        && 
+        (
+          stmt.children[0].type == 'identifier' 
+          || 
+          stmt.children[0].type == 'decl_pair' 
+          && 
+          stmt.children[0].name_node.type == 'identifier'
+        )
+      ) {
+        // Just a single declaration
+        if(identifiers.length != 1) {
+          throw new Error('illegal state')
+        }
+        value = identifiers[0][1]
+      } else {
+        value = Object.fromEntries(identifiers)
+      }
+
+      return {
+        index: stmt.index,
+        length: stmt.length,
+        result: {ok: true, value},
+      }
+    } else if(stmt.type == 'if'){
+      return null
+    } else if(stmt.type == 'import'){
+      result = {
+        ok: true,
+        value: state.modules[stmt.full_import_path],
+      }
+    } else if (stmt.type == 'export') {
+      return get_stmt_value_explorer(state, stmt.children[0])
+    } else {
+      result = stmt.result
+    }
+  } else {
+    result = find_error_origin_node(stmt).result
+  }
+
+  return {index: stmt.index, length: stmt.length, result}
+}
+
+
 const get_value_explorer = (state, index) => {
   if(
     state.active_calltree_node == null
@@ -677,49 +744,8 @@ const get_value_explorer = (state, index) => {
   const do_node = anc[do_index]
   const stmt = anc[do_index - 1]
 
-  if(stmt.result == null) {
-    // statement was not evaluated
-    return null
-  }
+  return get_stmt_value_explorer(state, stmt)
 
-  let result
-
-  if(stmt.result.ok) {
-    if(['const', 'assignment'].includes(stmt.type)) {
-      result = stmt.children[1].result
-    } else if(stmt.type == 'return') {
-      result = stmt.children[0].result
-    } else if(stmt.type == 'let') {
-      return {
-        index: stmt.index,
-        length: stmt.length,
-        result: 
-          {
-            ok: true, 
-            value: Object.fromEntries(
-              stmt.children.map(c => 
-                [c.value, c.result.value]
-              )
-            )
-          }
-      }
-    } else if(stmt.type == 'if'){
-      return null
-    } else if(stmt.type == 'import'){
-      result = {
-        ok: true,
-        value: state.modules[stmt.full_import_path],
-      }
-    } else if (stmt.type == 'export') {
-      result = stmt.children[0].children[1].result
-    } else {
-      result = stmt.result
-    }
-  } else {
-    result = find_error_origin_node(stmt).result
-  }
-
-  return {index: stmt.index, length: stmt.length, result}
 }
 
 const do_move_cursor = (state, index) => {

src/eval.js

@@ -217,32 +217,49 @@ const codegen = (node, node_cxt, parent) => {
     + branches[0]
     +'\n: '
     + branches[1]
-  } else if(node.type == 'const'){
-    const res = 'const ' + do_codegen(node.name_node) + ' = ' + do_codegen(node.expr, node) + ';'
-    if(node.name_node.type == 'identifier' && node.expr.type == 'function_call') {
-      // deduce function name from variable it was assigned to if anonymous
-      // works for point-free programming, like
-      // const parse_statement = either(parse_import, parse_assignment, ...)
-      return res + `
+  } else if(['const', 'let', 'assignment'].includes(node.type)) {
+    const prefix = node.type == 'assignment'
+      ? ''
+      : node.type + ' '
+    return prefix + node
+      .children
+      .map(c => c.type == 'identifier'
+        ? c.value
+        : do_codegen(c.children[0]) + ' = ' + do_codegen(c.children[1])
+      )
+      .join(',') 
+    + ';'
+    + node.children.map(decl => {
         if(
-          typeof(${node.name_node.value}) == 'function' 
+          node.type != 'assignment'
+          &&
+          decl.type != 'identifier' 
           && 
-          ${node.name_node.value}.name == 'anonymous'
+          decl.name_node.type == 'identifier' 
+          && 
+          decl.expr.type == 'function_call'
         ) {
-          Object.defineProperty(
-            ${node.name_node.value}, 
-            "name", 
-            {value: "${node.name_node.value}"}
-          );
+          // deduce function name from variable it was assigned to if anonymous
+          // works for point-free programming, like
+          // const parse_statement = either(parse_import, parse_assignment, ...)
+          return `
+            if(
+              typeof(${decl.name_node.value}) == 'function' 
+              && 
+              ${decl.name_node.value}.name == 'anonymous'
+            ) {
+              Object.defineProperty(
+                ${decl.name_node.value}, 
+                "name", 
+                {value: "${decl.name_node.value}"}
+              );
+            }
+          `
+        } else {
+          return ''
         }
-      `
-    } else {
-      return res
-    }
-  } else if(node.type == 'let') {
-    return 'let ' + node.names.join(',') + ';';
-  } else if(node.type == 'assignment') {
-    return node.name + ' = ' + do_codegen(node.expr, node) + ';';
+      })
+      .join('')
   } else if(node.type == 'member_access'){
     return '(' 
       + do_codegen(node.object) 
@@ -295,7 +312,10 @@ ${JSON.stringify(errormessage)}, true)`
     if(node.is_default) {
       return `__cxt.modules['${node_cxt.module}'].default = ${do_codegen(node.children[0])};`
     } else {
-      const identifiers = collect_destructuring_identifiers(node.binding.name_node)
+      const identifiers = node
+        .binding
+        .children
+        .flatMap(n => collect_destructuring_identifiers(n.name_node))
         .map(i => i.value)
       return do_codegen(node.binding)
         +
@@ -805,8 +825,8 @@ const eval_frame_expr = (node, scope, callsleft, context) => {
   }
 }
 
-const apply_assignments = (do_node, assignments) => {
-  const let_ids = do_node
+const apply_assignments = (node, assignments) => {
+  const let_ids = node
     .children
     .filter(c => c.type == 'let')
     .map(l => l.children)
@@ -823,34 +843,99 @@ const apply_assignments = (do_node, assignments) => {
     .map(([k, {name, value}]) => [name, value])
   )
 
-  const node = {...do_node, 
-    children: do_node.children.map(_let => {
-      if(_let.type != 'let') {
-        return _let
-      }
-      const children = _let.children.map(id => {
-        const a = assignments[id.index]
-        if(a == null) {
-          return id
-        } else {
-          return {...id, result: {ok: true, value: a.value}}
-        }
-      })
-      return {..._let, 
-        result: children.every(c => c.result != null) ? {ok: true} : null,
-        children
-      }
-    })
-  }
-
   return {node, scope}
 }
 
+const eval_decl_pair = (s, scope, calls, context, is_assignment) => {
+  if(s.type != 'decl_pair') {
+    throw new Error('illegal state')
+  }
+  // TODO default values for destructuring can be function calls
+
+  const {node, calls: next_calls} 
+    = eval_frame_expr(s.expr, scope, calls, context)
+  const s_expr_evaled = {...s, children: [s.name_node, node]}
+  if(!node.result.ok) {
+    return {
+      ok: false,
+      node: {...s_expr_evaled, result: {ok: false}},
+      scope,
+      calls: next_calls,
+    }
+  }
+
+  const name_nodes = collect_destructuring_identifiers(s.name_node)
+  const names = name_nodes.map(n => n.value)
+  const destructuring = codegen(s.name_node)
+
+  // TODO unique name for __value (gensym)
+  const codestring = `
+    const ${destructuring} = __value; 
+    ({${names.join(',')}});
+  `
+  const {ok, value: next_scope, error} = eval_codestring(
+    codestring, 
+    {...scope, __value: node.result.value}
+  )
+
+  // TODO fine-grained destructuring error, only for identifiers that failed
+  // destructuring
+  const name_node_with_result = map_tree(
+    map_destructuring_identifiers(
+      s.name_node,
+      node => ({...node, 
+        result: {
+          ok, 
+          error: ok  ? null : error,
+          value: !ok ? null : next_scope[node.value],
+        }
+      })
+    ),
+    n => n.result == null
+      ? {...n, result: {ok}}
+      : n
+  )
+
+  const s_evaled = {...s_expr_evaled, children: [
+    name_node_with_result,
+    s_expr_evaled.children[1],
+  ]}
+
+  if(!ok) {
+    return {
+      ok: false,
+      // TODO assign error to node where destructuring failed, not to every node
+      node: {...s_evaled, result: {ok, error, is_error_origin: true}},
+      scope,
+      calls,
+    }
+  }
+
+  return {
+    ok: true,
+    node: {...s_evaled, result: {ok: true}},
+    scope: {...scope, ...next_scope},
+    calls: next_calls,
+    assignments: is_assignment
+      ? Object.fromEntries(
+          name_nodes.map(n => [
+            n.definition.index, 
+            {
+              value: next_scope[n.value],
+              name: n.value,
+            }
+          ])
+        )
+      : null
+  }
+}
+
+
 const eval_statement = (s, scope, calls, context) => {
   if(s.type == 'do') {
-    const node = s
+    const stmt = s
     // hoist function decls to the top
-    const function_decls = node.children
+    const function_decls = s.children
       .filter(s => s.type == 'function_decl')
       .map(s => {
         const {ok, children, calls: next_calls} = eval_children(s, scope, calls, context)
@@ -872,7 +957,7 @@ const eval_statement = (s, scope, calls, context) => {
 
     const initial_scope = {...scope, ...hoisted_functions_scope}
 
-    const {ok, assignments, returned, children, calls: next_calls} = node.children.reduce(
+    const {ok, assignments, returned, children, calls: next_calls} = s.children.reduce(
       ({ok, returned, children, scope, calls, assignments}, s) => {
         if(returned || !ok) {
           return {ok, returned, scope, calls, children: [...children, s], assignments}
@@ -909,7 +994,7 @@ const eval_statement = (s, scope, calls, context) => {
       {ok: true, returned: false, children: [], scope: initial_scope, calls, assignments: {}}
     )
     const {node: next_node, scope: next_scope} = 
-      apply_assignments({...node, children: children, result: {ok}}, assignments)
+      apply_assignments({...s, children: children, result: {ok}}, assignments)
     return {
       ok,
       node: next_node,
@@ -918,86 +1003,46 @@ const eval_statement = (s, scope, calls, context) => {
       assignments,
       calls: next_calls,
     }
-  } else if(s.type == 'const' || s.type == 'assignment') {
-    // TODO default values for destructuring can be function calls
+  } else if(['let', 'const', 'assignment'].includes(s.type)) {
+    const stmt = s
 
-    const {node, calls: next_calls} 
-      = eval_frame_expr(s.expr, scope, calls, context)
-    const s_expr_evaled = {...s, children: [s.name_node, node]}
-    if(!node.result.ok) {
-      return {
-        ok: false,
-        node: {...s_expr_evaled, result: {ok: false}},
-        scope,
-        calls: next_calls,
-      }
-    }
+    const initial = {ok: true, children: [], scope, calls, assignments: null}
 
-    const name_nodes = collect_destructuring_identifiers(s.name_node)
-    const names = name_nodes.map(n => n.value)
-    const destructuring = codegen(s.name_node)
-
-    // TODO unique name for __value (gensym)
-    const codestring = `
-      const ${destructuring} = __value; 
-      ({${names.join(',')}});
-    `
-    const {ok, value: next_scope, error} = eval_codestring(
-      codestring, 
-      {...scope, __value: node.result.value}
+    const {ok, children, calls: next_calls, scope: next_scope, assignments} = s.children.reduce(
+      ({ok, children, scope, calls, assignments}, s) => {
+        if(!ok) {
+          return {ok, scope, calls, children: [...children, s]}
+        } 
+        if(stmt.type == 'let' && s.type == 'identifier') {
+          const node = {...s, result: {ok: true}}
+          return {ok, children: [...children, node], scope, calls}
+        }
+        const {
+          ok: next_ok, 
+          node,
+          scope: nextscope, 
+          calls: next_calls, 
+          assignments: next_assignments,
+        } = eval_decl_pair(s, scope, calls, context, stmt.type == 'assignment')
+        return {
+          ok: next_ok,
+          scope: nextscope,
+          calls: next_calls,
+          children: [...children, node],
+          assignments: stmt.type == 'assignment' 
+            ? {...assignments, ...next_assignments}
+            : null
+        }
+      },
+      initial
     )
-
-    // TODO fine-grained destructuring error, only for identifiers that failed
-    // destructuring
-    const name_node_with_result = map_tree(
-      map_destructuring_identifiers(
-        s.name_node,
-        node => ({...node, 
-          result: {
-            ok, 
-            error: ok  ? null : error,
-            value: !ok ? null : next_scope[node.value],
-          }
-        })
-      ),
-      n => n.result == null
-        ? {...n, result: {ok}}
-        : n
-    )
-
-    const s_evaled = {...s_expr_evaled, children: [
-      name_node_with_result,
-      s_expr_evaled.children[1],
-    ]}
-
-    if(!ok) {
-      return {
-        ok: false,
-        // TODO assign error to node where destructuring failed, not to every node
-        node: {...s_evaled, result: {ok, error, is_error_origin: true}},
-        scope,
-        calls,
-      }
-    }
-
     return {
-      ok: true,
-      node: {...s_evaled, result: {ok: true}},
+      ok,
+      node: {...s, children, result: {ok}},
       scope: {...scope, ...next_scope},
       calls: next_calls,
-      assignments: s.type == 'assignment'
-        ? Object.fromEntries(
-            name_nodes.map(n => [
-              n.definition.index, 
-              {
-                value: next_scope[n.value],
-                name: n.value,
-              }
-            ])
-          )
-        : null
+      assignments,
     }
-
   } else if(s.type == 'return') {
 
     const {node, calls: next_calls} = 
@@ -1121,10 +1166,6 @@ const eval_statement = (s, scope, calls, context) => {
       }
     }
 
-  } else if(s.type == 'let') {
-
-    return { ok: true, node: s, scope, calls }
-
   } else if(s.type == 'throw') {
 
     const {node, calls: next_calls} = eval_frame_expr(s.expr, scope, calls, context)

src/find_definitions.js

@@ -26,11 +26,13 @@ const scope_from_node = n => {
     )
   } else if(n.type == 'export'){
     return scope_from_node(n.binding)
-  } else if(n.type == 'const' || n.type == 'let'){
+  } else if(n.type == 'let' || n.type == 'const') {
     return Object.fromEntries(
-      collect_destructuring_identifiers(n.name_node).map(node => [
-        node.value, node
-      ])
+      n.children
+        .flatMap(collect_destructuring_identifiers)
+        .map(node => [
+          node.value, node
+        ])
     )
   } else if(n.type == 'function_decl') {
     // Return null because of hoisting. We take function decls into account
@@ -55,6 +57,11 @@ const add_trivial_definition = node => {
     ]}
   } else if(['array_destructuring', 'object_destructuring'].includes(node.type)) {
     return {...node, children: node.children.map(add_trivial_definition)}
+  } else if (node.type == 'decl_pair') {
+    return {
+      ...node, 
+      children: node.children.with(0, add_trivial_definition(node.children[0]))
+    }
   } else {
     console.error(node)
     throw new Error('not implemented')
@@ -150,10 +157,8 @@ export const find_definitions = (ast, globals, scope = {}, closure_scope = {}, m
           is_default: i == 0 && ast.default_import != null,
         }
       }))
-    } else if(ast.type == 'const') {
-      children = [add_trivial_definition(ast.name_node), ...ast.children.slice(1)]
-    } else if(ast.type == 'let') {
-      children = ast.name_node.map(add_trivial_definition)
+    } else if(ast.type == 'const' || ast.type == 'let') {
+      children = ast.children.map(add_trivial_definition)
     } else {
       children = ast.children
     }

src/parse_js.js

@@ -1091,55 +1091,47 @@ const function_decl = if_ok(
   node => ({...node, type: 'function_decl', children: [node]})
 )
 
-// TODO multiple decls, like `const x = 1, y = 2`
-const const_statement =
-  if_ok(
-    seq([
-      literal('const'),
-      destructuring,
-      literal('='),
-      expr,
-    ]),
-    ({value, ...node}) => {
-      const [_const, identifier, _eq, expr] = value
-      return {
-        ...node,
-        type: 'const',
-        name: identifier.value,
-        children: [identifier, expr],
-      }
+const decl_pair = if_ok(
+  seq([destructuring, literal('='), expr]),
+  ({value, ...node}) => {
+    const [lefthand, _eq, expr] = value
+    return {
+      ...node,
+      type: 'decl_pair',
+      not_evaluatable: true,
+      children: [lefthand, expr],
     }
-  )
+  }
+)
 
-const let_declaration = if_ok(
+const const_or_let = is_const => if_ok(
   seq_select(1, [
-    literal('let'),
-    comma_separated_1(identifier),
+    literal(is_const ? 'const' : 'let'),
+    comma_separated_1(
+      is_const
+        ? decl_pair
+        : either(decl_pair, identifier)
+    )
   ]),
   ({value, ...node}) => ({
     ...node,
-    type: 'let',
+    type: is_const ? 'const' : 'let',
     children: value.value,
-    names: value.value.map(n => n.value),
   })
 )
 
+const const_statement = const_or_let(true)
+
+const let_declaration = const_or_let(false)
+
+// TODO object assignment required braces, like ({foo} = {foo: 1})
 const assignment = if_ok(
-  seq([
-    // TODO object assignment required braces, like ({foo} = {foo: 1})
-    destructuring,
-    literal('='),
-    expr,
-  ]),
-  ({value, ...node}) => {
-    const [identifier, _eq, expr] = value
-    return {
-      ...node,
-      type: 'assignment',
-      name: identifier.value,
-      children: [identifier, expr],
-    }
-  },
+  comma_separated_1(decl_pair),
+  ({value, ...node}) => ({
+    ...node,
+    type: 'assignment',
+    children: value,
+  })
 )
 
 const return_statement =
@@ -1422,21 +1414,14 @@ const update_children_not_rec = (node, children = node.children) => {
     }
   } else if(node.type == 'const'){
     return {...node,
-      name_node: children[0],
-      expr: children[1],
       is_statement: true,
     }
   } else if(node.type == 'let'){
-    return {...node,
-      name_node: children,
-      is_statement: true,
-    }
+    return {...node, is_statement: true }
+  } else if(node.type == 'decl_pair') {
+    return {...node, expr: node.children[1], name_node: node.children[0]}
   } else if(node.type == 'assignment'){
-    return {...node,
-      name_node: children[0],
-      expr: children[1],
-      is_statement: true,
-    }
+    return {...node, is_statement: true}
   } else if(node.type == 'do'){
     return {...node, is_statement: true}
   } else if(node.type == 'function_decl'){
@@ -1568,8 +1553,10 @@ const do_deduce_fn_names = (node, parent) => {
     node_result.name == null
   ) {
     let name
-    if(parent?.type == 'const') {
-      name = parent.name
+    if(parent?.type == 'decl_pair') {
+      if(parent.name_node.type == 'identifier') {
+        name = parent.name_node.value
+      }
     } else if(parent?.type == 'key_value_pair') {
       // unwrap quotes with JSON.parse
       name = JSON.parse(parent.key.value)

test/test.js

@@ -320,6 +320,15 @@ export const tests = [
     )
   }),
 
+  test('let variable', () => {
+    const code = `
+      let x, y = 2, unused, [z,q] = [3,4]
+      x = 1
+    `
+    const i = test_initial_state(code, code.indexOf('x'))
+    assert_equal(i.value_explorer.result.value, {y: 2, z: 3, q: 4})
+  }),
+
   test('else if', () => {
     const code = `
       let x
@@ -764,7 +773,10 @@ export const tests = [
     const {calltree, modules} = eval_modules(parsed);
     const frame = eval_frame(calltree, modules)
     assert_equal(frame.children[1].result, {ok: true})
-    assert_equal(frame.children[1].children[0].children[1].result, {ok: true, value: 2})
+    assert_equal(
+      find_node(frame, n => n.string == 'b').result.value,
+      2
+    )
   }),
 
   test('eval_frame error', () => {
@@ -972,7 +984,6 @@ export const tests = [
     assert_equal(result.ok, true)
   }),
 
-
   test('module external', () => {
     const code = `
       // external
@@ -1195,6 +1206,12 @@ export const tests = [
     assert_equal(active_frame(next).children.at(-1).result.value, 'foo_value')
   }),
 
+  test('export value explorer', () => {
+    const code = 'export const x = 1'
+    const i = test_initial_state(code)
+    assert_equal(i.value_explorer.result.value, 1)
+  }),
+
   // Static analysis
 
   test('undeclared', () => {
@@ -1446,8 +1463,53 @@ export const tests = [
     )
     // assert let has result
     assert_equal(frame.children[0].result, {ok: true})
-    // assert x value
-    assert_equal(frame.children[0].children[0].result, {ok: true, value: 1})
+  }),
+
+  test('multiple assignments', () => {
+    assert_code_evals_to(
+      `
+        let x, y
+        x = 1, {y} = {y: 2}
+        {x,y}
+      `,
+      {x: 1, y: 2}
+    )
+  }),
+
+  test('assigments value explorer', () => {
+    const code = `
+      let x
+      x = 1
+    `
+    const i = test_initial_state(code, code.indexOf('x = 1'))
+    assert_equal(i.value_explorer.result.value, 1)
+  }),
+
+  test('multiple assigments value explorer', () => {
+    const code = `
+      let x, y
+      x = 1, y = 2
+    `
+    const i = test_initial_state(code, code.indexOf('x = 1'))
+    assert_equal(i.value_explorer.result.value, {x: 1, y: 2})
+  }),
+
+  test('assigments destructuring value explorer', () => {
+    const code = `
+      let x, y
+      x = 1, {y} = {y:2}
+    `
+    const i = test_initial_state(code, code.indexOf('x = 1'))
+    assert_equal(i.value_explorer.result.value, {x: 1, y: 2})
+  }),
+
+  test('assigments error', () => {
+    const code = `
+      let x, y
+      x = 1, y = null.foo
+    `
+    const i = test_initial_state(code, code.indexOf('x = 1'))
+    assert_equal(i.value_explorer.result.ok, false)
   }),
 
   test('block scoping', () => {
@@ -2471,15 +2533,15 @@ const y = x()`
 
   test('move_cursor let', () => {
     const code = `
-      let x
-      x = 1
+      let x = 1
     `
     const s1 = test_initial_state(code)
     const s2 = COMMANDS.move_cursor(s1, code.indexOf('x'))
+    const lettext = 'let x = 1'
     assert_equal(s2.value_explorer, {
-      index: code.indexOf('let x'),
-      length: 5,
-      result: {ok: true, value: {x: 1}},
+      index: code.indexOf(lettext),
+      length: lettext.length,
+      result: {ok: true, value: 1},
     })
   }),