Support ${lua expression} in templates

common/syscalls/lua.ts

@@ -1,10 +1,29 @@
 import type { SysCallMapping } from "$lib/plugos/system.ts";
-import { parse } from "../space_lua/parse.ts";
+import { evalExpression } from "$common/space_lua/eval.ts";
+import { parse, parseExpressionString } from "../space_lua/parse.ts";
+import type { CommonSystem } from "$common/common_system.ts";
+import { LuaStackFrame, luaValueToJS } from "$common/space_lua/runtime.ts";
 
-export function luaSyscalls(): SysCallMapping {
+export function luaSyscalls(commonSystem: CommonSystem): SysCallMapping {
   return {
     "lua.parse": (_ctx, code: string) => {
       return parse(code);
     },
+    /**
+     * Evaluates a Lua expression and returns the result as a JavaScript value
+     * @param _ctx
+     * @param expression
+     * @returns
+     */
+    "lua.evalExpression": (_ctx, expression: string) => {
+      const ast = parseExpressionString(expression);
+      return luaValueToJS(
+        evalExpression(
+          ast,
+          commonSystem.spaceLuaEnv.env,
+          LuaStackFrame.lostFrame,
+        ),
+      );
+    },
   };
 }

common/template/render.ts

@@ -2,8 +2,7 @@ import type { AST } from "../../plug-api/lib/tree.ts";
 import { evalQueryExpression } from "@silverbulletmd/silverbullet/lib/query_expression";
 import { expressionToKvQueryExpression } from "../../plug-api/lib/parse_query.ts";
 import type { FunctionMap } from "../../plug-api/types.ts";
-import { jsonToMDTable } from "../../plugs/template/util.ts";
-import { LuaTable } from "$common/space_lua/runtime.ts";
+import { renderExpressionResult } from "../../plugs/template/util.ts";
 
 export async function renderTemplate(
   ast: AST,
@@ -83,35 +82,6 @@ async function renderExpressionDirective(
   return renderExpressionResult(result);
 }
 
-export function renderExpressionResult(result: any): string {
-  if (result instanceof LuaTable) {
-    result = result.toJS();
-  }
-  if (
-    Array.isArray(result) && result.length > 0 && typeof result[0] === "object"
-  ) {
-    // If result is an array of objects, render as a markdown table
-    try {
-      return jsonToMDTable(result);
-    } catch (e: any) {
-      console.error(
-        `Error rendering expression directive: ${e.message} for value ${
-          JSON.stringify(result)
-        }`,
-      );
-      return JSON.stringify(result);
-    }
-  } else if (typeof result === "object" && result.constructor === Object) {
-    // if result is a plain object, render as a markdown table
-    return jsonToMDTable([result]);
-  } else if (Array.isArray(result)) {
-    // Not-object array, let's render it as a markdown list
-    return result.map((item) => `- ${item}`).join("\n");
-  } else {
-    return "" + result;
-  }
-}
-
 async function renderEachVarDirective(
   ast: AST,
   value: any[],

plug-api/syscalls/lua.ts

@@ -6,3 +6,9 @@ export function parse(
 ): Promise<ParseTree> {
   return syscall("lua.parse", code);
 }
+
+export function evalExpression(
+  expression: string,
+): Promise<any> {
+  return syscall("lua.evalExpression", expression);
+}

plugs/markdown/api.ts

@@ -4,7 +4,7 @@ import {
   renderToText,
   replaceNodesMatchingAsync,
 } from "../../plug-api/lib/tree.ts";
-import { codeWidget } from "@silverbulletmd/silverbullet/syscalls";
+import { codeWidget, lua } from "@silverbulletmd/silverbullet/syscalls";
 import { parseMarkdown } from "../../plug-api/syscalls/markdown.ts";
 import {
   type MarkdownRenderOptions,
@@ -12,6 +12,8 @@ import {
 } from "./markdown_render.ts";
 import { validatePageName } from "@silverbulletmd/silverbullet/lib/page_ref";
 import { parsePageRef } from "@silverbulletmd/silverbullet/lib/page_ref";
+import type { LuaExpression } from "$common/space_lua/ast.ts";
+import { renderExpressionResult } from "../template/util.ts";
 
 /**
  * Finds code widgets, runs their plug code to render and inlines their content in the parse tree
@@ -102,6 +104,26 @@ export async function expandCodeWidgets(
           page,
         );
       }
+    } else if (n.type === "LuaDirective") {
+      const expr: LuaExpression | null = findNodeOfType(
+        n,
+        "LuaExpressionDirective",
+      ) as LuaExpression | null;
+      if (!expr) {
+        return;
+      }
+      const exprText = renderToText(expr);
+
+      let result = await lua.evalExpression(exprText);
+
+      if (result.markdown) {
+        result = result.markdown;
+      }
+
+      const markdown = renderExpressionResult(result);
+
+      console.log("Expanding LuaDirective", exprText, result, markdown);
+      return await parseMarkdown(markdown);
     }
   });
   return mdTree;

plugs/template/util.ts

@@ -1,6 +1,7 @@
 import type { PageMeta } from "../../plug-api/types.ts";
 import { space, system, template } from "@silverbulletmd/silverbullet/syscalls";
 import { cleanTemplate } from "./plug_api.ts";
+import { LuaTable } from "$common/space_lua/runtime.ts";
 
 export function defaultJsonTransformer(v: any): string {
   if (v === undefined) {
@@ -91,3 +92,32 @@ export async function renderQueryTemplate(
     config,
   });
 }
+
+export function renderExpressionResult(result: any): string {
+  if (result instanceof LuaTable) {
+    result = result.toJS();
+  }
+  if (
+    Array.isArray(result) && result.length > 0 && typeof result[0] === "object"
+  ) {
+    // If result is an array of objects, render as a markdown table
+    try {
+      return jsonToMDTable(result);
+    } catch (e: any) {
+      console.error(
+        `Error rendering expression directive: ${e.message} for value ${
+          JSON.stringify(result)
+        }`,
+      );
+      return JSON.stringify(result);
+    }
+  } else if (typeof result === "object" && result.constructor === Object) {
+    // if result is a plain object, render as a markdown table
+    return jsonToMDTable([result]);
+  } else if (Array.isArray(result)) {
+    // Not-object array, let's render it as a markdown list
+    return result.map((item) => `- ${item}`).join("\n");
+  } else {
+    return "" + result;
+  }
+}

server/server_system.ts

@@ -139,7 +139,7 @@ export class ServerSystem extends CommonSystem {
       jsonschemaSyscalls(),
       indexSyscalls(this),
       commandSyscalls(this),
-      luaSyscalls(),
+      luaSyscalls(this),
       templateSyscalls(this.ds),
       dataStoreReadSyscalls(this.ds, this),
       codeWidgetSyscalls(codeWidgetHook),

web/client_system.ts

@@ -168,7 +168,7 @@ export class ClientSystem extends CommonSystem {
       jsonschemaSyscalls(),
       indexSyscalls(this),
       commandSyscalls(this),
-      luaSyscalls(),
+      luaSyscalls(this),
       this.client.syncMode
         // In sync mode handle locally
         ? mqSyscalls(this.mq)

web/cm_plugins/lua_widget.ts

@@ -11,7 +11,7 @@ import { extendedMarkdownLanguage } from "$common/markdown_parser/parser.ts";
 import { renderToText } from "@silverbulletmd/silverbullet/lib/tree";
 import { activeWidgets } from "./markdown_widget.ts";
 import { attachWidgetEventHandlers } from "./widget_util.ts";
-import { renderExpressionResult } from "$common/template/render.ts";
+import { renderExpressionResult } from "../../plugs/template/util.ts";
 
 export type LuaWidgetCallback = (
   bodyText: string,