From cb5c4c71c866362dce24eff79251fed6add53e9f Mon Sep 17 00:00:00 2001
From: dave caruso <me@paperdave.net>
Date: Tue, 17 Oct 2023 19:42:37 -0700
Subject: yay

---
 src/codegen/builtin-parser.ts | 187 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 187 insertions(+)
 create mode 100644 src/codegen/builtin-parser.ts

(limited to 'src/codegen/builtin-parser.ts')

diff --git a/src/codegen/builtin-parser.ts b/src/codegen/builtin-parser.ts
new file mode 100644
index 000000000..4e35f13dd
--- /dev/null
+++ b/src/codegen/builtin-parser.ts
@@ -0,0 +1,187 @@
+import { applyReplacements } from "./replacements";
+
+/**
+ * Slices a string until it hits a }, but keeping in mind JS comments,
+ * regex, template literals, comments, and matching {
+ *
+ * Used to extract function bodies without parsing the code.
+ *
+ * If you pass replace=true, it will run replacements on the code
+ */
+export function sliceSourceCode(
+  contents: string,
+  replace: boolean,
+  replaceRequire?: (specifier: string) => string,
+  endOnComma = false,
+): { result: string; rest: string } {
+  let bracketCount = 0;
+  let i = 0;
+  let result = "";
+  while (contents.length) {
+    const match = contents.match(
+      endOnComma && bracketCount <= 1
+        ? /((?:[(,=;:{]|return|\=\>)\s*)\/[^\/\*]|\/\*|\/\/|['"}`\),]|(?<!\$)\brequire\(|(\$assert\(|\$debug\()/
+        : /((?:[(,=;:{]|return|\=\>)\s*)\/[^\/\*]|\/\*|\/\/|['"}`\)]|(?<!\$)\brequire\(|(\$assert\(|\$debug\()/,
+    );
+    i = match?.index ?? contents.length;
+    if (match?.[2]) {
+      i += match[2].length - 1;
+    }
+    bracketCount += [...contents.slice(0, i).matchAll(/[({]/g)].length;
+    const chunk = replace ? applyReplacements(contents, i) : [contents.slice(0, i), contents.slice(i)];
+    result += chunk[0];
+    contents = chunk[1] as string;
+    if (chunk[2]) {
+      continue;
+    }
+    if (match?.[1]) {
+      if (match[1].startsWith("(") || match[1].startsWith(",")) {
+        bracketCount++;
+      }
+      const { result: result2, rest } = sliceRegularExpressionSourceCode(
+        contents.slice(match?.[1].length + 1),
+        replace,
+      );
+      result += contents.slice(0, match?.[1].length + 1) + result2;
+      contents = rest;
+      continue;
+    }
+    if (!contents.length) break;
+    if (contents.startsWith("/*")) {
+      i = contents.slice(2).indexOf("*/") + 2;
+    } else if (contents.startsWith("//")) {
+      i = contents.slice(2).indexOf("\n") + 2;
+    } else if (contents.startsWith("'")) {
+      i = getEndOfBasicString(contents.slice(1), "'") + 2;
+    } else if (contents.startsWith('"')) {
+      i = getEndOfBasicString(contents.slice(1), '"') + 2;
+    } else if (contents.startsWith("`")) {
+      const { result: result2, rest } = sliceTemplateLiteralSourceCode(contents.slice(1), replace);
+      result += "`" + result2;
+      contents = rest;
+      i = 0;
+      continue;
+    } else if (contents.startsWith("}")) {
+      bracketCount--;
+      if (bracketCount <= 0) {
+        result += "}";
+        contents = contents.slice(1);
+        break;
+      }
+      i = 1;
+    } else if (contents.startsWith(")")) {
+      bracketCount--;
+      if (bracketCount <= 0) {
+        result += ")";
+        contents = contents.slice(1);
+        break;
+      }
+      i = 1;
+    } else if (endOnComma && contents.startsWith(",")) {
+      if (bracketCount <= 1) {
+        contents = contents.slice(1);
+        // if the next non-whitespace character is ), we will treat it like a )
+        let match = contents.match(/^\s*\)/);
+        if (match) {
+          contents = contents.slice(match[0].length);
+          result += ")";
+        } else {
+          result += ",";
+        }
+        break;
+      }
+      i = 1;
+    } else if (contents.startsWith("require(")) {
+      if (replaceRequire) {
+        const staticSpecifier = contents.match(/\brequire\(["']([^"']+)["']\)/);
+        if (staticSpecifier) {
+          const specifier = staticSpecifier[1];
+          result += replaceRequire(specifier);
+          contents = contents.slice(staticSpecifier[0].length);
+          continue;
+        } else {
+          throw new Error("Require with dynamic specifier not supported here.");
+        }
+      } else {
+        throw new Error("Require is not supported here.");
+      }
+    } else {
+      console.error(contents.slice(0, 100));
+      throw new Error("TODO");
+    }
+    result += contents.slice(0, i);
+    contents = contents.slice(i);
+  }
+
+  return { result, rest: contents };
+}
+
+function sliceTemplateLiteralSourceCode(contents: string, replace: boolean) {
+  let i = 0;
+  let result = "";
+  while (contents.length) {
+    i = contents.match(/`|\${/)!.index!;
+    result += contents.slice(0, i);
+    contents = contents.slice(i);
+    if (!contents.length) break;
+    if (contents.startsWith("`")) {
+      result += "`";
+      contents = contents.slice(1);
+      break;
+    } else if (contents.startsWith("$")) {
+      const { result: result2, rest } = sliceSourceCode(contents.slice(1), replace);
+      result += "$" + result2;
+      contents = rest;
+      continue;
+    } else {
+      throw new Error("TODO");
+    }
+  }
+
+  return { result, rest: contents };
+}
+
+function sliceRegularExpressionSourceCode(contents: string, replace: boolean) {
+  let i = 0;
+  let result = "";
+  while (contents.length) {
+    i = contents.match(/\/(?!\/|\*)|\\|\[/)!.index!;
+    result += contents.slice(0, i);
+    contents = contents.slice(i);
+    if (!contents.length) break;
+    if (contents.startsWith("/")) {
+      result += "/";
+      contents = contents.slice(1);
+      break;
+    } else if (contents.startsWith("\\")) {
+      result += "\\";
+      contents = contents.slice(1);
+      if (!contents.length) break;
+      result += contents[0];
+      contents = contents.slice(1);
+      continue;
+    } else if (contents.startsWith("[")) {
+      let end = contents.match(/(?<!\\)]/)!.index!;
+      result += contents.slice(0, end + 1);
+      contents = contents.slice(end + 1);
+      continue;
+    } else {
+      throw new Error("TODO");
+    }
+  }
+
+  return { result, rest: contents };
+}
+
+function getEndOfBasicString(str: string, quote: "'" | '"') {
+  let i = 0;
+  while (i < str.length) {
+    if (str[i] === "\\") {
+      i++;
+    } else if (str[i] === quote) {
+      return i;
+    }
+    i++;
+  }
+  throw new Error("String did not end");
+}
-- 
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