Merge pull request #1022 from RustPython/coolreader18/demo-repl-continuation

Add line continuation for the WASM demo terminal

wasm/demo/src/main.js

@@ -82,12 +82,6 @@ snippets.addEventListener('change', updateSnippet);
 // option selected for the `select`, but the textarea won't be updated)
 updateSnippet();
 
-const prompt = '>>>>> ';
-
-const term = new Terminal();
-term.open(document.getElementById('terminal'));
-term.write(prompt);
-
 function removeNonAscii(str) {
     if (str === null || str === '') return false;
     else str = str.toString();
@@ -99,38 +93,80 @@ function printToConsole(data) {
     term.write(removeNonAscii(data) + '\r\n');
 }
 
+const term = new Terminal();
+term.open(document.getElementById('terminal'));
+
 const terminalVM = rp.vmStore.init('term_vm');
 terminalVM.setStdout(printToConsole);
 
-var input = '';
+function getPrompt(name = 'ps1') {
+    terminalVM.exec(`
+try:
+    import sys as __sys
+    __prompt = __sys.${name}
+except:
+    __prompt = ''
+finally:
+    del __sys
+`);
+    return String(terminalVM.eval('__prompt'));
+}
+
+term.write(getPrompt());
+
+function resetInput() {
+    continuedInput = [];
+    input = '';
+    continuing = false;
+}
+
+let continuedInput, input, continuing;
+resetInput();
+
+let ps2;
+
 term.on('data', data => {
     const code = data.charCodeAt(0);
     if (code == 13) {
         // CR
-        if (input[input.length - 1] == ':') {
-            input += data;
-            term.write('\r\n.....');
-        } else {
-            term.write('\r\n');
-            try {
-                terminalVM.execSingle(input);
-            } catch (err) {
-                if (err instanceof WebAssembly.RuntimeError) {
-                    err = window.__RUSTPYTHON_ERROR || err;
-                }
-                printToConsole(err);
+        term.write('\r\n');
+        continuedInput.push(input);
+        if (continuing) {
+            if (input === '') {
+                continuing = false;
+            } else {
+                input = '';
+                term.write(ps2);
+                return;
             }
-            term.write(prompt);
-            input = '';
         }
-    } else if (code == 127) {
+        try {
+            terminalVM.execSingle(continuedInput.join('\n'));
+        } catch (err) {
+            if (err instanceof SyntaxError && err.message.includes('EOF')) {
+                ps2 = getPrompt('ps2');
+                term.write(ps2);
+                continuing = true;
+                input = '';
+                return;
+            } else if (err instanceof WebAssembly.RuntimeError) {
+                err = window.__RUSTPYTHON_ERROR || err;
+            }
+            printToConsole(err);
+        }
+        resetInput();
+        term.write(getPrompt());
+    } else if (code == 127 || code == 8) {
+        // Backspace
         if (input.length > 0) {
             term.write('\b \b');
             input = input.slice(0, -1);
         }
-    } else if (code < 32 || code == 127) {
+    } else if (code < 32) {
         // Control
-        return;
+        term.write('\r\n' + getPrompt());
+        input = '';
+        continuedInput = [];
     } else {
         // Visible
         term.write(data);