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+// file : libbuild2/make-parser.hxx -*- C++ -*-
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_MAKE_PARSER_HXX
+#define LIBBUILD2_MAKE_PARSER_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/export.hxx>
+
+namespace build2
+{
+ // Make dependency declaration parser.
+ //
+ // The format is line-based (but with potential line continuations) so we
+ // parse one line at a time. This allows the caller to bail out early (for
+ // example, on encountering a non-existent generated file).
+ //
+ class LIBBUILD2_SYMEXPORT make_parser
+ {
+ public:
+ enum {begin, targets, prereqs, end} state = begin;
+
+ // Parse next target/prerequisite on a line starting from the specified
+ // position. Update the position to point to the start of the following
+ // target/prerequisite or l.size() if there is nothing left on this
+ // line. May return an empty string for a valid if unlikely dependency
+ // declarations (see below) or if passing leading blank lines (both of
+ // which should normally be just skipped). Issue diagnostics and throw
+ // failed if the declaration is invalid.
+ //
+ // If strict is false, then allow unescaped `:` in prerequisites.
+ //
+ // Note that the (p != l.size) should be in the do-while rather than in a
+ // while loop. In other words, except for the leading blank lines, the
+ // parser needs to see the blank line to correctly identify the end of the
+ // declaration. See make-parser.test.cxx for a recommended usage.
+ //
+ // To parse more than one declaration, reset the state to begin after
+ // reaching end.
+ //
+ enum class type {target, prereq};
+
+ pair<type, string>
+ next (const string&, size_t&, const location&, bool strict);
+
+ // Lower-level stateless API.
+ //
+ public:
+ // Parse next target/prerequisite on a line starting from the specified
+ // position. Return the target/prerequisite as well as an indication of
+ // whether the end of the dependency declaration was reached. Update the
+ // position to point to the start of the following target/prerequisite,
+ // `:`, or l.size() if there is nothing left on this line.
+ //
+ // Note that some broken tools (notably MinGW GCC) do not escape `:`
+ // properly. To tolerate such cases the caller may specify that what's
+ // being parsed is the prerequisite list in which case unescaped `:` will
+ // be treated literally.
+ //
+ // Note also that this function may return an empty string (with
+ // end=false) for a valid if unlikely dependency declaration, for example
+ // (using | to represent backslash):
+ //
+ // foo:|
+ // |
+ // bar
+ //
+ // It would also return an empty string (with end=true) if passed and
+ // empty or whitespace-only line.
+ //
+ // Note also that in the make language line continuations introduce a
+ // whitespace rather than just being remove. For example, the following
+ // declaration has two prerequisites:
+ //
+ // foo: bar|
+ // baz
+ //
+ static pair<string, bool>
+ next (const string&, size_t&, optional<bool> prereq = nullopt);
+ };
+}
+
+#endif // LIBBUILD2_MAKE_PARSER_HXX