Import of the watch repository from Pebble

src/fw/applib/template_string.h

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+//! Variables that change how a template string is evaluated
+typedef struct TemplateStringVars {
+  time_t current_time;
+} TemplateStringVars;
+
+//! Variables that are used for determining when the string must be re-evaluated
+typedef struct TemplateStringEvalConditions {
+  //! If true, string MUST be re-evaluated on eval_time,  regardless of other conditions.
+  //! Otherwise, only re-evaluate if all the other conditions are also true.
+  bool force_eval_on_time;
+  //! Timestamp for next time to re-evaluate the string
+  //! If this is 0, there is no need to re-evaluate based on time
+  time_t eval_time;
+} TemplateStringEvalConditions;
+
+//! Bitfield describing errors in a template string
+typedef enum TemplateStringErrorStatus {
+  //! No error occurred. `index_in_string` is invalid.
+  TemplateStringErrorStatus_Success = 0,
+  //! Couldn't resolve the template string to a final string.
+  TemplateStringErrorStatus_CantResolve,
+  //! Closing curly-brace was missing.
+  TemplateStringErrorStatus_MissingClosingBrace,
+  //! Missing argument.
+  TemplateStringErrorStatus_MissingArgument,
+  //! No result was generated.
+  TemplateStringErrorStatus_NoResultGenerated,
+  //! Unknown filter used.
+  TemplateStringErrorStatus_UnknownFilter,
+  //! format() was not the last filter.
+  TemplateStringErrorStatus_FormatBeforeLast,
+  //! Time unit in predicate is invalid.
+  TemplateStringErrorStatus_InvalidTimeUnit,
+  //! Escape character at end of string.
+  TemplateStringErrorStatus_InvalidEscapeCharacter,
+  //! Opening parenthesis for filter was missing.
+  TemplateStringErrorStatus_MissingOpeningParen,
+  //! Closing parenthesis for filter was missing.
+  TemplateStringErrorStatus_MissingClosingParen,
+  //! Invalid conversion specifier for format.
+  TemplateStringErrorStatus_InvalidConversionSpecifier,
+  //! Invalid parameter.
+  TemplateStringErrorStatus_InvalidParameter,
+  //! Opening quote for filter was missing.
+  TemplateStringErrorStatus_MissingOpeningQuote,
+  //! Closing quote for filter was missing.
+  TemplateStringErrorStatus_MissingClosingQuote,
+  //! Invalid argument separator.
+  TemplateStringErrorStatus_InvalidArgumentSeparator,
+
+  TemplateStringErrorStatusCount,
+} TemplateStringErrorStatus;
+
+//! Contains information about a template string error
+typedef struct TemplateStringError {
+  //! 0-indexed position in the input string where the error occurred.
+  size_t index_in_string;
+  TemplateStringErrorStatus status;
+} TemplateStringError;
+
+//! @param input_template_string The template string to evaluate
+//! @param output A pointer to a string buffer for which to write the evaluated string output upon
+//!               success. May be NULL for no output
+//! @param output_size The size of the output string buffer in bytes; no bytes beyond this size
+//!                    will be written to the output string buffer. This should also include the
+//!                    ending NUL terminator. May be 0 for no output
+//! @param reeval_cond Pointer to a structure that will be filled with information on when to
+//!                    re-evaluate the string. Maybe be NULL
+//! @param vars Pointer to variables that affect how the template string will be evaluated
+//! @param errors Pointer to a TemplateStringError that will be set to contain information about
+//!               the first error detected in the template string upon failure
+//! @return True if the template string is successfully evaluated and the output written to the
+//!         provided output string buffer, false otherwise
+bool template_string_evaluate(const char *input_template_string, char *output, size_t output_size,
+                              TemplateStringEvalConditions *reeval_cond,
+                              const TemplateStringVars *vars, TemplateStringError *error);