Support nested if statements

package.json

@@ -1,6 +1,6 @@
 {
   "name": "mapshaper",
-  "version": "0.6.62",
+  "version": "0.6.63",
   "description": "A tool for editing vector datasets for mapping and GIS.",
   "keywords": [
     "shapefile",

src/cli/mapshaper-run-commands.mjs

@@ -8,7 +8,6 @@ import { error, UserError, message, print, loggingEnabled, printError } from '..
 import { Job } from '../mapshaper-job';
 import { runningInBrowser } from '../mapshaper-env';
 import utils from '../utils/mapshaper-utils';
-import { resetControlFlow } from '../mapshaper-control-flow';
 import require from '../mapshaper-require';
 import { commandTakesFileInput } from '../cli/mapshaper-command-info';
 import { version } from '../../package.json';

src/commands/mapshaper-if-elif-else-endif.mjs

@@ -3,27 +3,26 @@ import cmd from '../mapshaper-cmd';
 import { layerIsEmpty } from '../dataset/mapshaper-layer-utils';
 import { stop } from '../utils/mapshaper-logging';
 import {
-  resetControlFlow,
   inControlBlock,
   enterActiveBranch,
   enterInactiveBranch,
   inActiveBranch,
-  blockWasActive,
-  jobIsStopped
+  blockIsComplete,
+  jobIsStopped,
+  enterBlock,
+  leaveBlock
 } from '../mapshaper-control-flow';
 import { compileIfCommandExpression } from '../expressions/mapshaper-layer-expressions';
 
 export function skipCommand(cmdName, job) {
   // allow all control commands to run
   if (jobIsStopped(job)) return true;
   if (isControlFlowCommand(cmdName)) return false;
-  return inControlBlock(job) && !inActiveBranch(job);
+  return !inActiveBranch(job);
 }
 
 cmd.if = function(job, opts) {
-  if (inControlBlock(job)) {
-    stop('Nested -if commands are not supported.');
-  }
+  enterBlock(job);
   evaluateIf(job, opts);
 };
 
@@ -38,7 +37,7 @@ cmd.else = function(job) {
   if (!inControlBlock(job)) {
     stop('-else command must be preceded by an -if command.');
   }
-  if (blockWasActive(job)) {
+  if (blockIsComplete(job)) {
     enterInactiveBranch(job);
   } else {
     enterActiveBranch(job);
@@ -49,32 +48,24 @@ cmd.endif = function(job) {
   if (!inControlBlock(job)) {
     stop('-endif command must be preceded by an -if command.');
   }
-  resetControlFlow(job);
+  leaveBlock(job);
 };
 
 function isControlFlowCommand(cmd) {
   return ['if','elif','else','endif'].includes(cmd);
 }
 
 function test(catalog, opts) {
-  // var targ = getTargetLayer(catalog, opts);
   if (opts.expression) {
     return compileIfCommandExpression(opts.expression, catalog, opts)();
   }
-  // if (opts.empty) {
-  //   return layerIsEmpty(targ.layer);
-  // }
-  // if (opts.not_empty) {
-  //   return !layerIsEmpty(targ.layer);
-  // }
   return true;
 }
 
 function evaluateIf(job, opts) {
-  if (!blockWasActive(job) && test(job.catalog, opts)) {
+  if (!blockIsComplete(job) && test(job.catalog, opts)) {
     enterActiveBranch(job);
   } else {
     enterInactiveBranch(job);
   }
 }
-

src/mapshaper-control-flow.mjs

@@ -1,41 +1,59 @@
 
-export function resetControlFlow(job) {
-  job.control = null;
-}
-
 export function stopJob(job) {
-  getState(job).stopped = true;
+  job.stopped = true;
 }
 
 export function jobIsStopped(job) {
-  return getState(job).stopped === true;
+  return job.stopped === true;
 }
 
 export function inControlBlock(job) {
-  return !!getState(job).inControlBlock;
+  return getStack(job).length > 0;
+}
+
+export function enterBlock(job) {
+  var stack = getStack(job);
+  // skip over a block if it is inside an inactive branch
+  stack.push({
+    active: false,
+    complete: !inActiveBranch(job)
+  });
+}
+
+export function leaveBlock(job) {
+  var stack = getStack(job);
+  stack.pop();
 }
 
 export function enterActiveBranch(job) {
-  var state = getState(job);
-  state.inControlBlock = true;
-  state.active = true;
-  state.complete = true;
+  var block = getCurrentBlock(job);
+  block.active = true;
+  block.complete = true;
 }
 
 export function enterInactiveBranch(job) {
-  var state = getState(job);
-  state.inControlBlock = true;
-  state.active = false;
+  var block = getCurrentBlock(job);
+  block.active = false;
+}
+
+export function blockIsComplete(job) {
+  var block = getCurrentBlock(job);
+  return block.complete;
 }
 
-export function blockWasActive(job) {
-  return !!getState(job).complete;
+function getCurrentBlock(job) {
+  var stack = getStack(job);
+  return stack[stack.length-1];
 }
 
+// A branch is considered to be active if it and all its parents are active
+// (Main branch is considered to be active)
 export function inActiveBranch(job) {
-  return !!getState(job).active;
+  var stack = getStack(job);
+  return stack.length === 0 || stack.every(block => block.active);
 }
 
-function getState(job) {
-  return job.control || (job.control = {});
+function getStack(job) {
+  job.control = job.control || {stack: []};
+  return job.control.stack;
 }

test/if-elif-else-test.mjs

@@ -18,6 +18,7 @@ describe('mapshaper-if-elif-else-endif.js', function () {
     });
   });
 
+
   it ('test expression', function(done) {
     var data = {
       type: 'GeometryCollection',
@@ -188,4 +189,36 @@ describe('mapshaper-if-elif-else-endif.js', function () {
       done();
     });
   });
+
+  it ('nested if statement 1', async function() {
+    var data = 'name\na';
+    var cmd = `-i data.csv
+      -if true -each 'name="b"'
+        -if false -each 'name="c"'
+        -elif true -each 'name="d"'
+        -else -each 'name="e"'
+        -endif
+      -else -each name="f"'
+      -endif
+      -o`;
+    var out = await api.applyCommands(cmd, {'data.csv': data});
+    assert.equal(out['data.csv'], 'name\nd');
+  })
+
+  it ('nested if statement 2', async function() {
+    var data = 'name\na';
+    var cmd = `-i data.csv
+      -if false -each 'name="b"'
+        -if true -each 'name="c"'
+        -elif true -each 'name="d"'
+        -else -each 'name="e"'
+        -endif
+      -else -each name="f"'
+      -endif
+      -o`;
+    var out = await api.applyCommands(cmd, {'data.csv': data});
+    assert.equal(out['data.csv'], 'name\nf');
+  })
+
+
 })