xref: /freebsd/contrib/kyua/utils/text/templates.hpp (revision dd41de95a84d979615a2ef11df6850622bf6184e)
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28 
29 /// \file utils/text/templates.hpp
30 /// Custom templating engine for text documents.
31 ///
32 /// This module provides a simple mechanism to generate text documents based on
33 /// templates.  The templates are just text files that contain template
34 /// statements that instruct this processor to perform transformations on the
35 /// input.
36 ///
37 /// While this was originally written to handle HTML templates, it is actually
38 /// generic enough to handle any kind of text document, hence why it lives
39 /// within the utils::text library.
40 ///
41 /// An example of how the templates look like:
42 ///
43 ///   %if names
44 ///   List of names
45 ///   -------------
46 ///   Amount of names: %%length(names)%%
47 ///   Most preferred name: %%preferred_name%%
48 ///   Full list:
49 ///   %loop names iter
50 ///     * %%last_names(iter)%%, %%names(iter)%%
51 ///   %endloop
52 ///   %endif names
53 
54 #if !defined(UTILS_TEXT_TEMPLATES_HPP)
55 #define UTILS_TEXT_TEMPLATES_HPP
56 
57 #include "utils/text/templates_fwd.hpp"
58 
59 #include <istream>
60 #include <map>
61 #include <ostream>
62 #include <string>
63 #include <vector>
64 
65 #include "utils/fs/path_fwd.hpp"
66 
67 namespace utils {
68 namespace text {
69 
70 
71 /// Definitions of the templates to apply to a file.
72 ///
73 /// This class provides the environment (e.g. the list of variables) that the
74 /// templating system has to use when generating the output files.  This
75 /// definition is static in the sense that this is what the caller program
76 /// specifies.
77 class templates_def {
78     /// Mapping of variable names to their values.
79     typedef std::map< std::string, std::string > variables_map;
80 
81     /// Collection of global variables available to the templates.
82     variables_map _variables;
83 
84     /// Convenience name for a vector of strings.
85     typedef std::vector< std::string > strings_vector;
86 
87     /// Mapping of vector names to their contents.
88     ///
89     /// Ideally, these would be represented as part of the _variables, but we
90     /// would need a complex mechanism to identify whether a variable is a
91     /// string or a vector.
92     typedef std::map< std::string, strings_vector > vectors_map;
93 
94     /// Collection of vectors available to the templates.
95     vectors_map _vectors;
96 
97     const std::string& get_vector(const std::string&, const std::string&) const;
98 
99 public:
100     templates_def(void);
101 
102     void add_variable(const std::string&, const std::string&);
103     void remove_variable(const std::string&);
104     void add_vector(const std::string&);
105     void add_to_vector(const std::string&, const std::string&);
106 
107     bool exists(const std::string&) const;
108     const std::string& get_variable(const std::string&) const;
109     const strings_vector& get_vector(const std::string&) const;
110 
111     std::string evaluate(const std::string&) const;
112 };
113 
114 
115 void instantiate(const templates_def&, std::istream&, std::ostream&);
116 void instantiate(const templates_def&, const fs::path&, const fs::path&);
117 
118 
119 }  // namespace text
120 }  // namespace utils
121 
122 #endif  // !defined(UTILS_TEXT_TEMPLATES_HPP)
123