{"version":3,"file":"template.cjs","names":["template: string","nodes: ParsedTemplateNode[]","bracket: \"}\" | \"{\" | \"{}\"","start: number","i","template: mustache.TemplateSpans","context: string[]","values: InputValues","DEFAULT_FORMATTER_MAPPING: Record","DEFAULT_PARSER_MAPPING: Record","templateFormat: TemplateFormat","inputValues: InputValues","addLangChainErrorFields","template: MessageContent","inputVariables: string[]","dummyInputs: InputValues","e: any"],"sources":["../../src/prompts/template.ts"],"sourcesContent":["import mustache from \"mustache\";\nimport { MessageContent } from \"../messages/index.js\";\nimport type { InputValues } from \"../utils/types/index.js\";\nimport { addLangChainErrorFields } from \"../errors/index.js\";\n\nfunction configureMustache() {\n // Use unescaped HTML\n // https://github.com/janl/mustache.js?tab=readme-ov-file#variables\n mustache.escape = (text) => text;\n}\n\n/**\n * Type that specifies the format of a template.\n */\nexport type TemplateFormat = \"f-string\" | \"mustache\";\n\n/**\n * Type that represents a node in a parsed format string. It can be either\n * a literal text or a variable name.\n */\nexport type ParsedTemplateNode =\n | { type: \"literal\"; text: string }\n | { type: \"variable\"; name: string };\n\n/**\n * Alias for `ParsedTemplateNode` since it is the same for\n * both f-string and mustache templates.\n */\nexport type ParsedFStringNode = ParsedTemplateNode;\n\nexport const parseFString = (template: string): ParsedTemplateNode[] => {\n // Core logic replicated from internals of pythons built in Formatter class.\n // https://github.com/python/cpython/blob/135ec7cefbaffd516b77362ad2b2ad1025af462e/Objects/stringlib/unicode_format.h#L700-L706\n const chars = template.split(\"\");\n const nodes: ParsedTemplateNode[] = [];\n\n const nextBracket = (bracket: \"}\" | \"{\" | \"{}\", start: number) => {\n for (let i = start; i < chars.length; i += 1) {\n if (bracket.includes(chars[i])) {\n return i;\n }\n }\n return -1;\n };\n\n let i = 0;\n while (i < chars.length) {\n if (chars[i] === \"{\" && i + 1 < chars.length && chars[i + 1] === \"{\") {\n nodes.push({ type: \"literal\", text: \"{\" });\n i += 2;\n } else if (\n chars[i] === \"}\" &&\n i + 1 < chars.length &&\n chars[i + 1] === \"}\"\n ) {\n nodes.push({ type: \"literal\", text: \"}\" });\n i += 2;\n } else if (chars[i] === \"{\") {\n const j = nextBracket(\"}\", i);\n if (j < 0) {\n throw new Error(\"Unclosed '{' in template.\");\n }\n\n nodes.push({\n type: \"variable\",\n name: chars.slice(i + 1, j).join(\"\"),\n });\n i = j + 1;\n } else if (chars[i] === \"}\") {\n throw new Error(\"Single '}' in template.\");\n } else {\n const next = nextBracket(\"{}\", i);\n const text = (next < 0 ? chars.slice(i) : chars.slice(i, next)).join(\"\");\n nodes.push({ type: \"literal\", text });\n i = next < 0 ? chars.length : next;\n }\n }\n return nodes;\n};\n\n/**\n * Convert the result of mustache.parse into an array of ParsedTemplateNode,\n * to make it compatible with other LangChain string parsing template formats.\n *\n * @param {mustache.TemplateSpans} template The result of parsing a mustache template with the mustache.js library.\n * @param {string[]} context Array of section variable names for nested context\n * @returns {ParsedTemplateNode[]}\n */\nconst mustacheTemplateToNodes = (\n template: mustache.TemplateSpans,\n context: string[] = []\n): ParsedTemplateNode[] => {\n const nodes: ParsedTemplateNode[] = [];\n\n for (const temp of template) {\n if (temp[0] === \"name\") {\n const name = temp[1].includes(\".\") ? temp[1].split(\".\")[0] : temp[1];\n nodes.push({ type: \"variable\", name });\n } else if ([\"#\", \"&\", \"^\", \">\"].includes(temp[0])) {\n // # represents a section, \"&\" represents an unescaped variable.\n // These should both be considered variables.\n nodes.push({ type: \"variable\", name: temp[1] });\n\n // If this is a section with nested content, recursively process it\n if (temp[0] === \"#\" && temp.length > 4 && Array.isArray(temp[4])) {\n const newContext = [...context, temp[1]];\n const nestedNodes = mustacheTemplateToNodes(temp[4], newContext);\n nodes.push(...nestedNodes);\n }\n } else {\n nodes.push({ type: \"literal\", text: temp[1] });\n }\n }\n\n return nodes;\n};\n\nexport const parseMustache = (template: string) => {\n configureMustache();\n const parsed = mustache.parse(template);\n return mustacheTemplateToNodes(parsed);\n};\n\nexport const interpolateFString = (template: string, values: InputValues) => {\n return parseFString(template).reduce((res, node) => {\n if (node.type === \"variable\") {\n if (node.name in values) {\n const stringValue =\n typeof values[node.name] === \"string\"\n ? values[node.name]\n : JSON.stringify(values[node.name]);\n return res + stringValue;\n }\n throw new Error(`(f-string) Missing value for input ${node.name}`);\n }\n\n return res + node.text;\n }, \"\");\n};\n\nexport const interpolateMustache = (template: string, values: InputValues) => {\n configureMustache();\n return mustache.render(template, values);\n};\n\n/**\n * Type that represents a function that takes a template string and a set\n * of input values, and returns a string where all variables in the\n * template have been replaced with their corresponding values.\n */\ntype Interpolator = (template: string, values: InputValues) => string;\n\n/**\n * Type that represents a function that takes a template string and\n * returns an array of `ParsedTemplateNode`.\n */\ntype Parser = (template: string) => ParsedTemplateNode[];\n\nexport const DEFAULT_FORMATTER_MAPPING: Record = {\n \"f-string\": interpolateFString,\n mustache: interpolateMustache,\n};\n\nexport const DEFAULT_PARSER_MAPPING: Record = {\n \"f-string\": parseFString,\n mustache: parseMustache,\n};\n\nexport const renderTemplate = (\n template: string,\n templateFormat: TemplateFormat,\n inputValues: InputValues\n) => {\n try {\n return DEFAULT_FORMATTER_MAPPING[templateFormat](template, inputValues);\n } catch (e) {\n const error = addLangChainErrorFields(e, \"INVALID_PROMPT_INPUT\");\n throw error;\n }\n};\n\nexport const parseTemplate = (\n template: string,\n templateFormat: TemplateFormat\n) => DEFAULT_PARSER_MAPPING[templateFormat](template);\n\nexport const checkValidTemplate = (\n template: MessageContent,\n templateFormat: TemplateFormat,\n inputVariables: string[]\n) => {\n if (!(templateFormat in DEFAULT_FORMATTER_MAPPING)) {\n const validFormats = Object.keys(DEFAULT_FORMATTER_MAPPING);\n throw new Error(`Invalid template format. 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