Add transient history

src/ansi-shell/readline.js

@@ -20,15 +20,18 @@ const ReadlineProcessorBuilder = builder => builder
             result: { value: '' },
             cursor: { value: 0 },
         },
+        // TODO: dormant configuration; waiting on ContextSignature
         imports: {
             out: {},
-            in_: {}
+            in_: {},
+            history: {}
         }
     }))
     .variable('result', { getDefaultValue: () => '' })
     .variable('cursor', { getDefaultValue: () => 0 })
     .external('out', { required: true })
     .external('in_', { required: true })
+    .external('history', { required: true })
     .beforeAll('get-byte', async ctx => {
         const { locals, externs } = ctx;
 
@@ -162,7 +165,7 @@ const ReadlineProcessorBuilder = builder => builder
         const finalByte = locals.byte;
         const controlSequence = vars.controlSequence.toArray();
 
-        // Log.log('controlSequence', controlSequence);
+        // Log.log('controlSequence', finalByte, controlSequence);
 
         if ( ! CSI_HANDLERS.hasOwnProperty(finalByte) ) {
             return;
@@ -187,10 +190,27 @@ const ReadlineProcessor = ReadlineProcessorBuilder(
     new StatefulProcessorBuilder()
 );
 
+class HistoryManager {
+    constructor () {
+        this.items = [];
+        this.index = 0;
+    }
+
+    get () {
+        return this.items[this.index];
+    }
+
+    save (data) {
+        this.items[this.index] = data;
+    }
+}
+
 class Readline {
     constructor (params) {
         this.internal_ = {};
         for ( const k in params ) this.internal_[k] = params[k];
+
+        this.history = new HistoryManager();
     }
 
     async readline (prompt) {
@@ -201,39 +221,16 @@ class Readline {
 
         const {
             result
-        } = await ReadlineProcessor.run({ out, in_ });
+        } = await ReadlineProcessor.run({
+            out, in_,
+            history: this.history
+        });
+
+        this.history.save(result);
+        this.history.index++;
 
         return result;
     }
-
-    // async readline (prompt) {
-    //     const out = this.internal_.out;
-    //     const in_ = this.internal_.in;
-
-    //     out.write(prompt);
-
-    //     let text = '';
-
-    //     const decoder = new TextDecoder();
-
-    //     while ( true ) {
-    //         const byteBuffer = new Uint8Array(1);
-    //         await in_.read(byteBuffer);
-
-    //         const byte = byteBuffer[0];
-    //         if ( byte === CHAR_LF ) {
-    //             out.write('\n');
-    //             break;
-    //         }
-
-    //         out.write(byteBuffer);
-    //         const part = decoder.decode(byteBuffer);
-    //         text += part;
-    //     }
-
-    //     // const text = await in_.readLine({ stream: out });
-    //     return text;
-    // }
 }
 
 export default class ReadlineLib {

src/ansi-shell/rl_csi_handlers.js

@@ -59,8 +59,71 @@ export const PC_FN_HANDLERS = {
     }
 };
 
+const save_history = ctx => {
+    const { history } = ctx.externs;
+    history.save(ctx.vars.result);
+};
+
+const correct_cursor = (ctx, oldCursor) => {
+    // TODO: make this work differently if oldCursor is not defined
+
+    const amount = ctx.vars.cursor - oldCursor;
+    ctx.vars.cursor = ctx.vars.result.length;
+    const L = amount < 0 ? 'D' : 'C';
+    if ( amount === 0 ) return;
+    const moveSequence = new Uint8Array([
+        consts.CHAR_ESC, consts.CHAR_CSI,
+        ...(new TextEncoder().encode('' + Math.abs(amount))),
+        cc(L)
+    ]);
+    ctx.externs.out.write(moveSequence);
+};
+
+const home = ctx => {
+    const amount = ctx.vars.cursor;
+    ctx.vars.cursor = 0;
+    const moveSequence = new Uint8Array([
+        consts.CHAR_ESC, consts.CHAR_CSI,
+        ...(new TextEncoder().encode('' + amount)),
+        cc('D')
+    ]);
+    if ( amount !== 0 ) ctx.externs.out.write(moveSequence);
+};
+
+const select_current_history = ctx => {
+        const { history } = ctx.externs;
+    home(ctx);
+    ctx.vars.result = history.get();
+    ctx.vars.cursor = ctx.vars.result.length;
+    const clearToEndSequence = new Uint8Array([
+        consts.CHAR_ESC, consts.CHAR_CSI,
+        ...(new TextEncoder().encode('0')),
+        cc('K')
+    ]);
+    ctx.externs.out.write(clearToEndSequence);
+    ctx.externs.out.write(history.get());
+};
+
 // --- CSI handlers: this is the last definition in this file ---
 export const CSI_HANDLERS = {
+    [cc('A')]: CSI_INT_ARG(ctx => {
+        save_history(ctx);
+        const { history } = ctx.externs;
+
+        if ( history.index === 0 ) return;
+
+        history.index--;
+        select_current_history(ctx);
+    }),
+    [cc('B')]: CSI_INT_ARG(ctx => {
+        save_history(ctx);
+        const { history } = ctx.externs;
+
+        if ( history.index === history.items.length - 1 ) return;
+
+        history.index++;
+        select_current_history(ctx);
+    }),
     // cursor back
     [cc('D')]: CSI_INT_ARG(ctx => {
         if ( ctx.vars.cursor === 0 ) {
@@ -115,14 +178,7 @@ export const CSI_HANDLERS = {
     }),
     // Home
     [cc('H')]: ctx => {
-        const amount = ctx.vars.cursor;
-        ctx.vars.cursor = 0;
-        const moveSequence = new Uint8Array([
-            consts.CHAR_ESC, consts.CHAR_CSI,
-            ...(new TextEncoder().encode('' + amount)),
-            cc('D')
-        ]);
-        ctx.externs.out.write(moveSequence);
+        home(ctx);
     },
     // End
     [cc('F')]: ctx => {
@@ -133,6 +189,6 @@ export const CSI_HANDLERS = {
             ...(new TextEncoder().encode('' + amount)),
             cc('C')
         ]);
-        ctx.externs.out.write(moveSequence);
+        if ( amount !== 0 ) ctx.externs.out.write(moveSequence);
     },
 };