Add an interpreter for optimized ps code

It'll be used as a fallback when wasm is disabled.
And add in the debugger a view for the generated js code and one for the ps code.

Author: calixteman

src/core/document.js

@@ -2136,6 +2136,22 @@ class PDFDocument {
         return obj;
       }
 
+      if (dict.get("FunctionType") === 4) {
+        const source = value.getString();
+        value.reset();
+        const domain = dict.get("Domain") ?? [];
+        const range = dict.get("Range") ?? [];
+        obj.psFunction = true;
+        obj.source = source;
+        obj.psLines = InternalViewerUtils.tokenizePSSource(source);
+        obj.jsCode = InternalViewerUtils.postScriptToJSCode(
+          source,
+          domain,
+          range
+        );
+        return obj;
+      }
+
       obj.bytes = value.getString();
       return obj;
     }

src/core/function.js

@@ -25,6 +25,7 @@ import {
 } from "../shared/util.js";
 import { PostScriptLexer, PostScriptParser } from "./ps_parser.js";
 import { BaseStream } from "./base_stream.js";
+import { buildPostScriptJsFunction } from "./postscript/js_evaluator.js";
 import { buildPostScriptWasmFunction } from "./postscript/wasm_compiler.js";
 import { isNumberArray } from "./core_utils.js";
 import { LocalFunctionCache } from "./image_utils.js";
@@ -370,8 +371,8 @@ class PDFFunction {
       throw new FormatError("No range.");
     }
 
-    if (factory.useWasm) {
-      try {
+    try {
+      if (factory.useWasm) {
         const wasmFn = buildPostScriptWasmFunction(
           fn.getString(),
           domain,
@@ -380,9 +381,14 @@ class PDFFunction {
         if (wasmFn) {
           return wasmFn; // (src, srcOffset, dest, destOffset) → void
         }
-      } catch {
-        // Fall through to the existing interpreter-based path.
+      } else {
+        const jsFn = buildPostScriptJsFunction(fn.getString(), domain, range);
+        if (jsFn) {
+          return jsFn; // (src, srcOffset, dest, destOffset) → void
+        }
       }
+    } catch {
+      // Fall through to the existing interpreter-based path.
     }
 
     warn("Unable to compile PS function, using interpreter");